Add comments explaining the fields for maple_metadata, since "end" is
ambiguous and "gap" can be confused as the largest gap, whereas it is
actually the offset of the largest gap.
Add comment for mas_ascend() to explain, whose min and max we are trying
to find. Explain that, for example, if we are already on offset zero,
then the parent min is mas->min, otherwise we need to walk up to find the
implied pivot min.
Link: https://lkml.kernel.org/r/20250703063338.51509-1-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
During the initial call with a maple state, an error status may be set
before a valid node is populated into the maple state node. Subsequent
calls with the maple state may restore the state into an active state with
no node set. This was masked by the mas_walk() always resetting the
status to ma_start and result in an extra walk in this rare scenario.
Don't restore the state to active unless there is a value in the structs
node. This also allows mas_walk() to be fixed to use the active state
without exposing an issue.
User visible results are marginal performance improvements when an active
state can be restored and used instead of rewalking the tree.
Stable is not Cc'ed because the existing code is stable and the
performance gains are not worth the risk.
Link: https://lore.kernel.org/all/20250611011253.19515-1-richard.weiyang@gmail.com/
Link: https://lore.kernel.org/all/20250407231354.11771-1-richard.weiyang@gmail.com/
Link: https://lore.kernel.org/all/202506191556.6bfc7b93-lkp@intel.com/
Link: https://lkml.kernel.org/r/20250624154823.52221-1-Liam.Howlett@oracle.com
Fixes: a8091f039c ("maple_tree: add MAS_UNDERFLOW and MAS_OVERFLOW states")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Wei Yang <richard.weiyang@gmail.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202506191556.6bfc7b93-lkp@intel.com
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use the underflow goto label to set the status to ma_underflow and return
NULL, as is being done elsewhere.
[akpm@linux-foundation.org: add newline, per Liam (and remove one, per akpm)]
Link: https://lkml.kernel.org/r/20250624080748.4855-1-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On destroy, we should set each node dead. But current code miss this when
the maple tree has only the root node.
The reason is mt_destroy_walk() leverage mte_destroy_descend() to set node
dead, but this is skipped since the only root node is a leaf.
Fixes this by setting the node dead if it is a leaf.
Link: https://lore.kernel.org/all/20250407231354.11771-1-richard.weiyang@gmail.com/
Link: https://lkml.kernel.org/r/20250624191841.64682-1-Liam.Howlett@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Temporarily clear the preallocation flag when explicitly requesting
allocations. Pre-existing allocations are already counted against the
request through mas_node_count_gfp(), but the allocations will not happen
if the MA_STATE_PREALLOC flag is set. This flag is meant to avoid
re-allocating in bulk allocation mode, and to detect issues with
preallocation calculations.
The MA_STATE_PREALLOC flag should also always be set on zero allocations
so that detection of underflow allocations will print a WARN_ON() during
consumption.
User visible effect of this flaw is a WARN_ON() followed by a null pointer
dereference when subsequent requests for larger number of nodes is
ignored, such as the vma merge retry in mmap_region() caused by drivers
altering the vma flags (which happens in v6.6, at least)
Link: https://lkml.kernel.org/r/20250616184521.3382795-3-Liam.Howlett@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Reported-by: Hailong Liu <hailong.liu@oppo.com>
Link: https://lore.kernel.org/all/1652f7eb-a51b-4fee-8058-c73af63bacd1@oppo.com/
Link: https://lore.kernel.org/all/20250428184058.1416274-1-Liam.Howlett@oracle.com/
Link: https://lore.kernel.org/all/20250429014754.1479118-1-Liam.Howlett@oracle.com/
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Hailong Liu <hailong.liu@oppo.com>
Cc: zhangpeng.00@bytedance.com <zhangpeng.00@bytedance.com>
Cc: Steve Kang <Steve.Kang@unisoc.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Move the unlikely case that mas->store_type is invalid to be the last
evaluated case and put liklier cases higher up.
Link: https://lkml.kernel.org/r/20250410191446.2474640-7-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Liam R. Howlett <liam.howlett@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In order to support rebalancing and spanning stores using less than the
worst case number of nodes, we need to track more than just the vacant
height. Using only vacant height to reduce the worst case maple node
allocation count can lead to a shortcoming of nodes in the following
scenarios.
For rebalancing writes, when a leaf node becomes insufficient, it may be
combined with a sibling into a single node. This means that the parent
node which has entries for this children will lose one entry. If this
parent node was just meeting the minimum entries, losing one entry will
now cause this parent node to be insufficient. This leads to a cascading
operation of rebalancing at different levels and can lead to more node
allocations than simply using vacant height can return.
For spanning writes, a similar situation occurs. At the location at which
a spanning write is detected, the number of ancestor nodes may similarly
need to rebalanced into a smaller number of nodes and the same cascading
situation could occur.
To use less than the full height of the tree for the number of
allocations, we also need to track the height at which a non-leaf node
cannot become insufficient. This means even if a rebalance occurs to a
child of this node, it currently has enough entries that it can lose one
without any further action. This field is stored in the maple write state
as sufficient height. In mas_prealloc_calc() when figuring out how many
nodes to allocate, we check if the vacant node is lower in the tree than a
sufficient node (has a larger value). If it is, we cannot use the vacant
height and must use the difference in the height and sufficient height as
the basis for the number of nodes needed.
An off by one bug was also discovered in mast_overflow() where it is using
>= rather than >. This caused extra iterations of the
mas_spanning_rebalance() loop and lead to unneeded allocations. A test is
also added to check the number of allocations is correct.
Link: https://lkml.kernel.org/r/20250410191446.2474640-6-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This allows support for using the vacant height to calculate the worst
case number of nodes needed for wr_rebalance operation.
mas_spanning_rebalance() was seen to perform unnecessary node allocations.
We can reduce allocations by breaking early during the rebalancing loop
once we realize that we have ascended to a common ancestor.
Link: https://lkml.kernel.org/r/20250410191446.2474640-5-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In order to determine the store type for a maple tree operation, a walk of
the tree is done through mas_wr_walk(). This function descends the tree
until a spanning write is detected or we reach a leaf node. While
descending, keep track of the height at which we encounter a node with
available space. This is done by checking if mas->end is less than the
number of slots a given node type can fit.
Now that the height of the vacant node is tracked, we can use the
difference between the height of the tree and the height of the vacant
node to know how many levels we will have to propagate creating new nodes.
Update mas_prealloc_calc() to consider the vacant height and reduce the
number of worst-case allocations.
Rebalancing and spanning stores are not supported and fall back to using
the full height of the tree for allocations.
Update preallocation testing assertions to take into account vacant
height.
Link: https://lkml.kernel.org/r/20250410191446.2474640-4-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For the maple tree, the root node is defined to have a depth of 0 with a
height of 1. Each level down from the node, these values are incremented
by 1. Various code paths define a root with depth 1 which is inconsisent
with the definition. Modify the code to be consistent with this
definition.
In mas_spanning_rebalance(), l_mas.depth was being used to track the
height based on the number of iterations done in the main loop. This
information was then used in mas_put_in_tree() to set the height. Rather
than overload the l_mas.depth field to track height, simply keep track of
height in the local variable new_height and directly pass this to
mas_wmb_replace() which will be passed into mas_put_in_tree(). This
allows up to remove writes to l_mas.depth.
Link: https://lkml.kernel.org/r/20250410191446.2474640-3-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Track node vacancy to reduce worst case allocation counts", v5.
================ overview ========================
Currently, the maple tree preallocates the worst case number of nodes for
given store type by taking into account the whole height of the tree.
This comes from a worst case scenario of every node in the tree being full
and having to propagate node allocation upwards until we reach the root of
the tree. This can be optimized if there are vacancies in nodes that are
at a lower depth than the root node. This series implements tracking the
level at which there is a vacant node so we only need to allocate until
this level is reached, rather than always using the full height of the
tree. The ma_wr_state struct is modified to add a field which keeps track
of the vacant height and is updated during walks of the tree. This value
is then read in mas_prealloc_calc() when we decide how many nodes to
allocate.
For rebalancing and spanning stores, we also need to track the lowest
height at which a node has 1 more entry than the minimum sufficient number
of entries. This is because rebalancing can cause a parent node to become
insufficient which results in further node allocations. In this case, we
need to use the sufficient height as the worst case rather than the vacant
height.
patch 1-2: preparatory patches
patch 3: implement vacant height tracking + update the tests
patch 4: support vacant height tracking for rebalancing writes
patch 5: implement sufficient height tracking
patch 6: reorder switch case statements
================ results =========================
Bpftrace was used to profile the allocation path for requesting new maple
nodes while running stress-ng mmap 120s. The histograms below represent
requests to kmem_cache_alloc_bulk() and show the count argument. This
represnts how many maple nodes the caller is requesting in
kmem_cache_alloc_bulk()
command: stress-ng --mmap 4 --timeout 120
mm-unstable
@bulk_alloc_req:
[3, 4) 4 | |
[4, 5) 54170 |@ |
[5, 6) 0 | |
[6, 7) 893057 |@@@@@@@@@@@@@@@@@@@@ |
[7, 8) 4 | |
[8, 9) 2230287 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[9, 10) 55811 |@ |
[10, 11) 77834 |@ |
[11, 12) 0 | |
[12, 13) 1368684 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ |
[13, 14) 0 | |
[14, 15) 0 | |
[15, 16) 367197 |@@@@@@@@ |
@maple_node_total: 46,630,160
@total_vmas: 46184591
mm-unstable + this series
@bulk_alloc_req:
[2, 3) 198 | |
[3, 4) 4 | |
[4, 5) 43 | |
[5, 6) 0 | |
[6, 7) 1069503 |@@@@@@@@@@@@@@@@@@@@@ |
[7, 8) 4 | |
[8, 9) 2597268 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[9, 10) 472191 |@@@@@@@@@ |
[10, 11) 191904 |@@@ |
[11, 12) 0 | |
[12, 13) 247316 |@@@@ |
[13, 14) 0 | |
[14, 15) 0 | |
[15, 16) 98769 |@ |
@maple_node_total: 37,813,856
@total_vmas: 43493287
This represents a ~19% reduction in the number of bulk maple nodes allocated.
For more reproducible results, a historgram of the return value of
mas_prealloc_calc() is displayed while running the maple_tree_tests whcih
have a deterministic store pattern
mas_prealloc_calc() return value mm-unstable
1 : (12068)
3 : (11836)
5 : ***** (271192)
7 : ************************************************** (2329329)
9 : *********** (534186)
10 : (435)
11 : *************** (704306)
13 : ******** (409781)
mas_prealloc_calc() return value mm-unstable + this series
1 : (12070)
3 : ************************************************** (3548777)
5 : ******** (633458)
7 : (65081)
9 : (11224)
10 : (341)
11 : (2973)
13 : (68)
do_mmap latency was also measured for regressions:
command: stress-ng --mmap 4 --timeout 120
mm-unstable:
avg = 7162 nsecs, total: 16101821292 nsecs, count: 2248034
mm-unstable + this series:
avg = 6689 nsecs, total: 15135391764 nsecs, count: 2262726
stress-ng --mmap4 --timeout 120
with vacant_height:
stress-ng: info: [257] 21526312 Maple Tree Read 0.176 M/sec
stress-ng: info: [257] 339979348 Maple Tree Write 2.774 M/sec
without vacant_height:
stress-ng: info: [8228] 20968900 Maple Tree Read 0.171 M/sec
stress-ng: info: [8228] 312214648 Maple Tree Write 2.547 M/sec
This represents an increase of ~3% read throughput and ~9% increase in
write throughput.
This patch (of 6):
In a subsequent patch, mas_prealloc_calc() will need to access fields only
in the ma_wr_state. Convert the function to take in a ma_wr_state and
modify all callers. There is no functional change.
Link: https://lkml.kernel.org/r/20250410191446.2474640-1-sidhartha.kumar@oracle.com
Link: https://lkml.kernel.org/r/20250410191446.2474640-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Remove a BUG_ON() right before a WARN_ON() with the same condition.
Calling WARN_ON() and BUG_ON() here is definitely wrong. Since the goal is
generally to remove BUG_ON() invocations from the kernel, keep only the
WARN_ON().
Link: https://lkml.kernel.org/r/20250213114453.1078318-1-ptesarik@suse.com
Fixes: 067311d33e ("maple_tree: separate ma_state node from status")
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Utilize ma_dead_node() in mte_dead_node(). It can prevent decoding the
maple enode for a second time. Use the "node" to find parent for
comparison.
Link: https://lkml.kernel.org/r/20250211071850.330632-1-richard120310@gmail.com
Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Shuah khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There's no mas->status of "mas_start", what the function is checking is
whether mas->status equals to "ma_start". Correct the comment for the
function.
Link: https://lkml.kernel.org/r/20250209181023.228856-1-richard120310@gmail.com
Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Reviewed-by: Liam R. Howlett <howlett@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Each level's rightmost node should have (max == ULONG_MAX). This means
current validation skips the right most node on each level.
Only the root node may be below the minimum data threshold.
Link: https://lkml.kernel.org/r/20241113031616.10530-4-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "simplify split calculation", v3.
This patch (of 3):
The current calculation for splitting nodes tries to enforce a minimum
span on the leaf nodes. This code is complex and never worked correctly
to begin with, due to the min value being passed as 0 for all leaves.
The calculation should just split the data as equally as possible
between the new nodes. Note that b_end will be one more than the data,
so the left side is still favoured in the calculation.
The current code may also lead to a deficient node by not leaving enough
data for the right side of the split. This issue is also addressed with
the split calculation change.
[Liam.Howlett@Oracle.com: rephrase the change log]
Link: https://lkml.kernel.org/r/20241113031616.10530-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20241113031616.10530-2-richard.weiyang@gmail.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When mas_anode_descend() not find gap, it sets -EBUSY instead of setting
offset to MAPLE_NODE_SLOTS.
Link: https://lkml.kernel.org/r/20241116014805.11547-4-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Empty tree and single entry tree is handled else whether, so the maple
tree here must be a tree with nodes.
If the height is 1 and we found the gap, it will jump to *done* since it
is also a leaf.
If the height is more than one, and there may be an available range, we
will descend the tree, which is not root anymore.
If there is no available range, we will set error and return.
This means the check for root node here is not necessary.
Link: https://lkml.kernel.org/r/20241116014805.11547-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mas_anode_descend() related cleanup".
Some cleanup related to mas_anode_descend().
This patch (of 3):
At the beginning of loop, it has checked the range is in lower bounds.
Link: https://lkml.kernel.org/r/20241116014805.11547-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20241116014805.11547-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The loop condition makes sure (mas.last < max), so we can directly use
mas_next_slot() here.
Since no other use of mas_next_entry(), it is removed.
Link: https://lkml.kernel.org/r/20241125024156.26093-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Change the LONG_MAX in simple_offset_add to 1024, and do latter:
[root@fedora ~]# mkdir /tmp/dir
[root@fedora ~]# for i in {1..1024}; do touch /tmp/dir/$i; done
touch: cannot touch '/tmp/dir/1024': Device or resource busy
[root@fedora ~]# rm /tmp/dir/123
[root@fedora ~]# touch /tmp/dir/1024
[root@fedora ~]# rm /tmp/dir/100
[root@fedora ~]# touch /tmp/dir/1025
touch: cannot touch '/tmp/dir/1025': Device or resource busy
After we delete file 100, actually this is a empty entry, but the latter
create failed unexpected.
mas_alloc_cyclic has two chance to find empty entry. First find the entry
with range range_lo and range_hi, if no empty entry exist, and range_lo >
min, retry find with range min and range_hi. However, the first call
mas_empty_area may mark mas as EBUSY, and the second call for
mas_empty_area will return false directly. Fix this by reload mas before
second call for mas_empty_area.
[Liam.Howlett@Oracle.com: fix mas_alloc_cyclic() second search]
Link: https://lore.kernel.org/all/20241216060600.287B4C4CED0@smtp.kernel.org/
Link: https://lkml.kernel.org/r/20241216190113.1226145-2-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20241214093005.72284-1-yangerkun@huaweicloud.com
Fixes: 9b6713cc75 ("maple_tree: Add mtree_alloc_cyclic()")
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com> says:
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, when storing NULL on mas_store_root(), the behavior could be
improved.
Storing NULLs over the entire tree may result in a node being used to
store a single range. Further stores of NULL may cause the node and
tree to be corrupt and cause incorrect behaviour. Fixing the store to
the root null fixes the issue by ensuring that a range of 0 - ULONG_MAX
results in an empty tree.
Users of the tree may experience incorrect values returned if the tree
was expanded to store values, then overwritten by all NULLS, then
continued to store NULLs over the empty area.
For example possible cases are:
* store NULL at any range result a new node
* store NULL at range [m, n] where m > 0 to a single entry tree result
a new node with range [m, n] set to NULL
* store NULL at range [m, n] where m > 0 to an empty tree result
consecutive NULL slot
* it allows for multiple NULL entries by expanding root
to store NULLs to an empty tree
This patch tries to improve in:
* memory efficient by setting to empty tree instead of using a node
* remove the possibility of consecutive NULL slot which will prohibit
extended null in later operation
Link: https://lkml.kernel.org/r/20241031231627.14316-5-richard.weiyang@gmail.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Before calling mas_new_root(), the range has been checked.
Link: https://lkml.kernel.org/r/20241031231627.14316-4-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
No user of the return value now, just remove it.
Link: https://lkml.kernel.org/r/20241031231627.14316-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "refine storing null", v5.
When overwriting the whole range with NULL, current behavior is not
correct.
An empty tree is represented by having the tree point to NULL directly.
An empty tree indicates the entire range (0-ULONG_MAX) is NULL.
A store operation into an existing node that causes 0 - ULONG_MAX to be
equal to NULL may not be restored to an empty state - a node is used to
store the single range instead. This is wasteful and different from the
initial setup of the tree.
Once the tree is using a single node to store 0 - ULONG_MAX, problems may
arise when storing more values into a tree with the unexpected state of 0
- ULONG being a single range in a node.
User visible issues may mean a corrupt tree and incorrect storage of
information within the tree. This would be limited to users who create
and then empty a tree by overwriting all values, then try to store more
NULLs into the empty tree.
I cannot come up with an example of any user doing this (users usually
destroy the tree and generally don't keep trying to store NULLs over
NULLs), but patch 4/5 "maple_tree: refine mas_store_root() on storing
NULL" should be backported just in case.
This patch (of 5):
Currently for an empty tree, it would print:
maple_tree(0x7ffcd02c6ee0) flags 1, height 0 root (nil)
0: (nil)
This is a little misleading.
Let's print (empty) for an empty tree.
Link: https://lkml.kernel.org/r/20241031231627.14316-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20241031231627.14316-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After commit 5d659bbb52 ("maple_tree: introduce mas_wr_store_type()"),
the check here is redundant.
Let's remove it.
Link: https://lkml.kernel.org/r/20241017015809.23392-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Following cleanup after introduce mas_wr_store_type()", v2.
Patch 1 postpone new_end calculation when needed.
Patch 2 removes a unnecessary sanity check in mas_wr_slot_store().
This patch (of 2):
For wr_exact_fit/wr_new_root, we don't need to calculate new_end.
Let's postpone it until necessary.
Link: https://lkml.kernel.org/r/20241017015809.23392-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20241017015809.23392-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When count is not 0, we know head is valid. So we can put the assignment
in if (count) instead of checking the head pointer again.
Also count represents current total, we can assign the new total by
increasing the count by one.
Link: https://lkml.kernel.org/r/20241015120746.15850-4-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If it jumps to nomem_one, the total allocated number is not changed. So
we don't need to adjust it.
For the nomem_bulk case, we know there is a valid mas->alloc. So we don't
need to do the check.
Link: https://lkml.kernel.org/r/20241015120746.15850-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "maple_tree: simplify mas_push_node()", v2.
When count is not 0, we know head is valid. So we can put the assignment
in if (count) instead of checking the head pointer again.
Also count represents current total, we can assign the new total by
increasing the count by one.
This patch (of 3):
If this is not a new allocated one, the request_count has already been
cleared in mas_set_alloc_req().
Link: https://lkml.kernel.org/r/20241015120746.15850-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20241015120746.15850-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For a root node, mte_parent_slot() return 0, this exactly fits the
following !p_slot check.
So we can remove the special handling for root node.
Link: https://lkml.kernel.org/r/20240913063128.27391-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In the following code, the second call to the mas_node_count will return
-ENOMEM:
mas_node_count(mas, MAPLE_ALLOC_SLOTS + 1);
mas_node_count(mas, MAPLE_ALLOC_SLOTS * 2 + 2);
This is because there may be some full maple_alloc node in current maple
state. Use full maple_alloc node will make max_req equal to 0. And it
leads to mt_alloc_bulk return 0. As a result, mas_node_count set mas.node
to MA_ERROR(-ENOMEM).
Find a non-full maple_alloc node, and if necessary, use this non-full node
in the next while loop.
Link: https://lkml.kernel.org/r/20240626160631.3636515-1-Liam.Howlett@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Jiazi Li <jqqlijiazi@gmail.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In mas_wr_store_type(), we check if new_end < mt_slots[wr_mas->type]. If
this check fails, we know that ,after this, new_end is >= mt_min_slots.
Checking this again when we detect a wr_node_store later in the function
is reduntant. Because this check is part of an OR statement, the
statement will always evaluate to true, therefore we can just get rid of
it.
We also refactor mas_wr_store_type() to return the store type rather than
set it directly as it greatly cleans up the function.
Link: https://lkml.kernel.org/r/20241011214451.7286-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha <sidhartha.kumar@oracle.com>
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Suggested-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Many maple tree values output when an mt_validate() or equivalent hits an
issue utilise tagged pointers, most notably parent nodes. Also some
pivots/slots contain meaningful values, output as pointers, such as the
index of the last entry with data for example.
All pointer values such as this are destroyed by kernel pointer hashing
rendering the debug output obtained from CONFIG_DEBUG_VM_MAPLE_TREE
considerably less usable.
Update this code to output the raw pointers using %px rather than %p when
CONFIG_DEBUG_VM_MAPLE_TREE is defined. This is justified, as the use of
this configuration flag indicates that this is a test environment.
Userland does not understand %px, so use %p there.
In an abundance of caution, if CONFIG_DEBUG_VM_MAPLE_TREE is not set, also
use %p to avoid exposing raw kernel pointers except when we are positive a
testing mode is enabled.
This was inspired by the investigation performed in recent debugging
efforts around a maple tree regression [0] where kernel pointer tagging had
to be disabled in order to obtain truly meaningful and useful data.
[0]:https://lore.kernel.org/all/20241001023402.3374-1-spasswolf@web.de/
Link: https://lkml.kernel.org/r/20241007115335.90104-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In mast_fill_bnode(), we first clear some fields of maple_big_node and set
the 'type' unconditionally before return. This means we won't leverage
any information in maple_big_node and it is safe to clear the whole
structure.
In maple_big_node, we define slot and padding/gap in a union. And based
on current definition of MAPLE_BIG_NODE_SLOTS/GAPS, padding is always less
than slot and part of the gap is overlapped by slot.
For example on 64bit system:
MAPLE_BIG_NODE_SLOT is 34
MAPLE_BIG_NODE_GAP is 21
With this knowledge, current code may clear some space by twice. And
this could be avoid by clearing the structure as a whole.
Link: https://lkml.kernel.org/r/20240908140554.20378-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Reduce the space to be cleared for maple_big_node", v2.
Found current code may clear maple_big_node redundantly.
First we define a field parent, which is never used. After removing this,
we reduce the size of memory to be cleared by memset.
Then mast_fill_bnode() clears part of the structure twice, since slot and
gap share some space. By clearing the whole structure, we can avoid this.
This patch (of 2):
The member parent of maple_big_node is never used.
Let's remove it which could reduce the number of space to be cleared on
memset.
Link: https://lkml.kernel.org/r/20240908140554.20378-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20240908140554.20378-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When we break the loop after assigning a pivot, the index i/j is not
changed. Then the following code assign pivot, which means we do the
assignment with same i/j by mas_safe_pivot.
Since the loop condition is (i < piv_end), from which we can get i is less
than mt_pivots[mt]. It implies mas_safe_pivot() return pivot[i] which is
the same value we get in loop.
Now we can conclude it does a redundant assignment on a pivot of 0. Let's
just go to complete to avoid it.
Link: https://lkml.kernel.org/r/20240911142759.20989-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "refine mas_mab_cp()".
By analysis of the code, one condition check can be removed and one case
would hit a redundant assignment.
This patch (of 2):
mas_mab_cp() copy range [mas_start, mas_end] inclusively from a
maple_node to maple_big_node. This implies mas_start <= mas_end.
Based on the relationship of mas_start and mas_end, we can have the
following four cases:
| mas_start == mas_end | mas_start < mas_end
---------------+----------------------+----------------------
mas_start == 0 | 1 | 2
---------------+----------------------+----------------------
mas_start != 0 | 3 | 4
We can see in all these four cases, i is always less than or equal to
mas_end after finish the loop:
Case 1: After assign pivot 0, i is set to 1, which is bigger than
mas_end 0. So it jumps to complete and skip the check.
Case 2: After assign pivot 0, i is set to 1.
∵ (mas_start < mas_end) && (mas_start == 0)
==> (1 <= mas_end)
∵ (i == 1) && (1 <= mas_end)
==> (i <= mas_end)
∴ Before loop, we have (i <= mas_end). And we still hold this
if it skips the loop. For example, (i == mas_end).
Now let's see what happens in the loop:
∵ piv_end = min(mas_end, mt_pivots[mt])
==> (piv_end <= mas_end)
∵ loop condition is (i < piv_end)
==> (i <= piv_end) on finish the loop both normally or break
∵ (i <= piv_end) && (piv_end <= mas_end)
==> (i <= mas_end)
∴ After loop, we still get (i <= mas_end) in this case
Case 3: This case would skip both if clause and loop. So when it comes
to the check, i is still mas_start which equals to mas_end.
Case 4: This case would skip the if clause.
∵ (mas_start < mas_end) && (i == mas_start)
==> (i < mas_end)
∴ Before loop, we have (i < mas_end).
The loop process is similar with Case 2, so we get the same
result.
Now we can conclude in all cases, we get (i <= mas_end) when doing
check. Then it is not necessary to do the check.
Link: https://lkml.kernel.org/r/20240911142759.20989-1-richard.weiyang@gmail.com
Link: https://lkml.kernel.org/r/20240911142759.20989-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "maple_tree: correct tree corruption on spanning store", v3.
There has been a nasty yet subtle maple tree corruption bug that appears
to have been in existence since the inception of the algorithm.
This bug seems far more likely to happen since commit f8d112a4e6
("mm/mmap: avoid zeroing vma tree in mmap_region()"), which is the point
at which reports started to be submitted concerning this bug.
We were made definitely aware of the bug thanks to the kind efforts of
Bert Karwatzki who helped enormously in my being able to track this down
and identify the cause of it.
The bug arises when an attempt is made to perform a spanning store across
two leaf nodes, where the right leaf node is the rightmost child of the
shared parent, AND the store completely consumes the right-mode node.
This results in mas_wr_spanning_store() mitakenly duplicating the new and
existing entries at the maximum pivot within the range, and thus maple
tree corruption.
The fix patch corrects this by detecting this scenario and disallowing the
mistaken duplicate copy.
The fix patch commit message goes into great detail as to how this occurs.
This series also includes a test which reliably reproduces the issue, and
asserts that the fix works correctly.
Bert has kindly tested the fix and confirmed it resolved his issues. Also
Mikhail Gavrilov kindly reported what appears to be precisely the same
bug, which this fix should also resolve.
This patch (of 2):
There has been a subtle bug present in the maple tree implementation from
its inception.
This arises from how stores are performed - when a store occurs, it will
overwrite overlapping ranges and adjust the tree as necessary to
accommodate this.
A range may always ultimately span two leaf nodes. In this instance we
walk the two leaf nodes, determine which elements are not overwritten to
the left and to the right of the start and end of the ranges respectively
and then rebalance the tree to contain these entries and the newly
inserted one.
This kind of store is dubbed a 'spanning store' and is implemented by
mas_wr_spanning_store().
In order to reach this stage, mas_store_gfp() invokes
mas_wr_preallocate(), mas_wr_store_type() and mas_wr_walk() in turn to
walk the tree and update the object (mas) to traverse to the location
where the write should be performed, determining its store type.
When a spanning store is required, this function returns false stopping at
the parent node which contains the target range, and mas_wr_store_type()
marks the mas->store_type as wr_spanning_store to denote this fact.
When we go to perform the store in mas_wr_spanning_store(), we first
determine the elements AFTER the END of the range we wish to store (that
is, to the right of the entry to be inserted) - we do this by walking to
the NEXT pivot in the tree (i.e. r_mas.last + 1), starting at the node we
have just determined contains the range over which we intend to write.
We then turn our attention to the entries to the left of the entry we are
inserting, whose state is represented by l_mas, and copy these into a 'big
node', which is a special node which contains enough slots to contain two
leaf node's worth of data.
We then copy the entry we wish to store immediately after this - the copy
and the insertion of the new entry is performed by mas_store_b_node().
After this we copy the elements to the right of the end of the range which
we are inserting, if we have not exceeded the length of the node (i.e.
r_mas.offset <= r_mas.end).
Herein lies the bug - under very specific circumstances, this logic can
break and corrupt the maple tree.
Consider the following tree:
Height
0 Root Node
/ \
pivot = 0xffff / \ pivot = ULONG_MAX
/ \
1 A [-----] ...
/ \
pivot = 0x4fff / \ pivot = 0xffff
/ \
2 (LEAVES) B [-----] [-----] C
^--- Last pivot 0xffff.
Now imagine we wish to store an entry in the range [0x4000, 0xffff] (note
that all ranges expressed in maple tree code are inclusive):
1. mas_store_gfp() descends the tree, finds node A at <=0xffff, then
determines that this is a spanning store across nodes B and C. The mas
state is set such that the current node from which we traverse further
is node A.
2. In mas_wr_spanning_store() we try to find elements to the right of pivot
0xffff by searching for an index of 0x10000:
- mas_wr_walk_index() invokes mas_wr_walk_descend() and
mas_wr_node_walk() in turn.
- mas_wr_node_walk() loops over entries in node A until EITHER it
finds an entry whose pivot equals or exceeds 0x10000 OR it
reaches the final entry.
- Since no entry has a pivot equal to or exceeding 0x10000, pivot
0xffff is selected, leading to node C.
- mas_wr_walk_traverse() resets the mas state to traverse node C. We
loop around and invoke mas_wr_walk_descend() and mas_wr_node_walk()
in turn once again.
- Again, we reach the last entry in node C, which has a pivot of
0xffff.
3. We then copy the elements to the left of 0x4000 in node B to the big
node via mas_store_b_node(), and insert the new [0x4000, 0xffff] entry
too.
4. We determine whether we have any entries to copy from the right of the
end of the range via - and with r_mas set up at the entry at pivot
0xffff, r_mas.offset <= r_mas.end, and then we DUPLICATE the entry at
pivot 0xffff.
5. BUG! The maple tree is corrupted with a duplicate entry.
This requires a very specific set of circumstances - we must be spanning
the last element in a leaf node, which is the last element in the parent
node.
spanning store across two leaf nodes with a range that ends at that shared
pivot.
A potential solution to this problem would simply be to reset the walk
each time we traverse r_mas, however given the rarity of this situation it
seems that would be rather inefficient.
Instead, this patch detects if the right hand node is populated, i.e. has
anything we need to copy.
We do so by only copying elements from the right of the entry being
inserted when the maximum value present exceeds the last, rather than
basing this on offset position.
The patch also updates some comments and eliminates the unused bool return
value in mas_wr_walk_index().
The work performed in commit f8d112a4e6 ("mm/mmap: avoid zeroing vma
tree in mmap_region()") seems to have made the probability of this event
much more likely, which is the point at which reports started to be
submitted concerning this bug.
The motivation for this change arose from Bert Karwatzki's report of
encountering mm instability after the release of kernel v6.12-rc1 which,
after the use of CONFIG_DEBUG_VM_MAPLE_TREE and similar configuration
options, was identified as maple tree corruption.
After Bert very generously provided his time and ability to reproduce this
event consistently, I was able to finally identify that the issue
discussed in this commit message was occurring for him.
Link: https://lkml.kernel.org/r/cover.1728314402.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/48b349a2a0f7c76e18772712d0997a5e12ab0a3b.1728314403.git.lorenzo.stoakes@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reported-by: Bert Karwatzki <spasswolf@web.de>
Closes: https://lore.kernel.org/all/20241001023402.3374-1-spasswolf@web.de/
Tested-by: Bert Karwatzki <spasswolf@web.de>
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Closes: https://lore.kernel.org/all/CABXGCsOPwuoNOqSMmAvWO2Fz4TEmPnjFj-b7iF+XFRu1h7-+Dg@mail.gmail.com/
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
It is possible for a bulk operation (MA_STATE_BULK is set) to enter the
new_end < mt_min_slots[type] case and set wr_rebalance as a store type.
This is incorrect as bulk stores do not rebalance per write, but rather
after the all of the writes are done through the mas_bulk_rebalance()
path. Therefore, add a check to make sure MA_STATE_BULK is not set before
we return wr_rebalance as the store type.
Also add a test to make sure wr_rebalance is never the store type when
doing bulk operations via mas_expected_entries()
This is a hotfix for this rc however it has no userspace effects as there
are no users of the bulk insertion mode.
Link: https://lkml.kernel.org/r/20241011214451.7286-1-sidhartha.kumar@oracle.com
Fixes: 5d659bbb52 ("maple_tree: introduce mas_wr_store_type()")
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Sidhartha <sidhartha.kumar@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
this pull request are:
"Align kvrealloc() with krealloc()" from Danilo Krummrich. Adds
consistency to the APIs and behaviour of these two core allocation
functions. This also simplifies/enables Rustification.
"Some cleanups for shmem" from Baolin Wang. No functional changes - mode
code reuse, better function naming, logic simplifications.
"mm: some small page fault cleanups" from Josef Bacik. No functional
changes - code cleanups only.
"Various memory tiering fixes" from Zi Yan. A small fix and a little
cleanup.
"mm/swap: remove boilerplate" from Yu Zhao. Code cleanups and
simplifications and .text shrinkage.
"Kernel stack usage histogram" from Pasha Tatashin and Shakeel Butt. This
is a feature, it adds new feilds to /proc/vmstat such as
$ grep kstack /proc/vmstat
kstack_1k 3
kstack_2k 188
kstack_4k 11391
kstack_8k 243
kstack_16k 0
which tells us that 11391 processes used 4k of stack while none at all
used 16k. Useful for some system tuning things, but partivularly useful
for "the dynamic kernel stack project".
"kmemleak: support for percpu memory leak detect" from Pavel Tikhomirov.
Teaches kmemleak to detect leaksage of percpu memory.
"mm: memcg: page counters optimizations" from Roman Gushchin. "3
independent small optimizations of page counters".
"mm: split PTE/PMD PT table Kconfig cleanups+clarifications" from David
Hildenbrand. Improves PTE/PMD splitlock detection, makes powerpc/8xx work
correctly by design rather than by accident.
"mm: remove arch_make_page_accessible()" from David Hildenbrand. Some
folio conversions which make arch_make_page_accessible() unneeded.
"mm, memcg: cg2 memory{.swap,}.peak write handlers" fro David Finkel.
Cleans up and fixes our handling of the resetting of the cgroup/process
peak-memory-use detector.
"Make core VMA operations internal and testable" from Lorenzo Stoakes.
Rationalizaion and encapsulation of the VMA manipulation APIs. With a
view to better enable testing of the VMA functions, even from a
userspace-only harness.
"mm: zswap: fixes for global shrinker" from Takero Funaki. Fix issues in
the zswap global shrinker, resulting in improved performance.
"mm: print the promo watermark in zoneinfo" from Kaiyang Zhao. Fill in
some missing info in /proc/zoneinfo.
"mm: replace follow_page() by folio_walk" from David Hildenbrand. Code
cleanups and rationalizations (conversion to folio_walk()) resulting in
the removal of follow_page().
"improving dynamic zswap shrinker protection scheme" from Nhat Pham. Some
tuning to improve zswap's dynamic shrinker. Significant reductions in
swapin and improvements in performance are shown.
"mm: Fix several issues with unaccepted memory" from Kirill Shutemov.
Improvements to the new unaccepted memory feature,
"mm/mprotect: Fix dax puds" from Peter Xu. Implements mprotect on DAX
PUDs. This was missing, although nobody seems to have notied yet.
"Introduce a store type enum for the Maple tree" from Sidhartha Kumar.
Cleanups and modest performance improvements for the maple tree library
code.
"memcg: further decouple v1 code from v2" from Shakeel Butt. Move more
cgroup v1 remnants away from the v2 memcg code.
"memcg: initiate deprecation of v1 features" from Shakeel Butt. Adds
various warnings telling users that memcg v1 features are deprecated.
"mm: swap: mTHP swap allocator base on swap cluster order" from Chris Li.
Greatly improves the success rate of the mTHP swap allocation.
"mm: introduce numa_memblks" from Mike Rapoport. Moves various disparate
per-arch implementations of numa_memblk code into generic code.
"mm: batch free swaps for zap_pte_range()" from Barry Song. Greatly
improves the performance of munmap() of swap-filled ptes.
"support large folio swap-out and swap-in for shmem" from Baolin Wang.
With this series we no longer split shmem large folios into simgle-page
folios when swapping out shmem.
"mm/hugetlb: alloc/free gigantic folios" from Yu Zhao. Nice performance
improvements and code reductions for gigantic folios.
"support shmem mTHP collapse" from Baolin Wang. Adds support for
khugepaged's collapsing of shmem mTHP folios.
"mm: Optimize mseal checks" from Pedro Falcato. Fixes an mprotect()
performance regression due to the addition of mseal().
"Increase the number of bits available in page_type" from Matthew Wilcox.
Increases the number of bits available in page_type!
"Simplify the page flags a little" from Matthew Wilcox. Many legacy page
flags are now folio flags, so the page-based flags and their
accessors/mutators can be removed.
"mm: store zero pages to be swapped out in a bitmap" from Usama Arif. An
optimization which permits us to avoid writing/reading zero-filled zswap
pages to backing store.
"Avoid MAP_FIXED gap exposure" from Liam Howlett. Fixes a race window
which occurs when a MAP_FIXED operqtion is occurring during an unrelated
vma tree walk.
"mm: remove vma_merge()" from Lorenzo Stoakes. Major rotorooting of the
vma_merge() functionality, making ot cleaner, more testable and better
tested.
"misc fixups for DAMON {self,kunit} tests" from SeongJae Park. Minor
fixups of DAMON selftests and kunit tests.
"mm: memory_hotplug: improve do_migrate_range()" from Kefeng Wang. Code
cleanups and folio conversions.
"Shmem mTHP controls and stats improvements" from Ryan Roberts. Cleanups
for shmem controls and stats.
"mm: count the number of anonymous THPs per size" from Barry Song. Expose
additional anon THP stats to userspace for improved tuning.
"mm: finish isolate/putback_lru_page()" from Kefeng Wang: more folio
conversions and removal of now-unused page-based APIs.
"replace per-quota region priorities histogram buffer with per-context
one" from SeongJae Park. DAMON histogram rationalization.
"Docs/damon: update GitHub repo URLs and maintainer-profile" from SeongJae
Park. DAMON documentation updates.
"mm/vdpa: correct misuse of non-direct-reclaim __GFP_NOFAIL and improve
related doc and warn" from Jason Wang: fixes usage of page allocator
__GFP_NOFAIL and GFP_ATOMIC flags.
"mm: split underused THPs" from Yu Zhao. Improve THP=always policy - this
was overprovisioning THPs in sparsely accessed memory areas.
"zram: introduce custom comp backends API" frm Sergey Senozhatsky. Add
support for zram run-time compression algorithm tuning.
"mm: Care about shadow stack guard gap when getting an unmapped area" from
Mark Brown. Fix up the various arch_get_unmapped_area() implementations
to better respect guard areas.
"Improve mem_cgroup_iter()" from Kinsey Ho. Improve the reliability of
mem_cgroup_iter() and various code cleanups.
"mm: Support huge pfnmaps" from Peter Xu. Extends the usage of huge
pfnmap support.
"resource: Fix region_intersects() vs add_memory_driver_managed()" from
Huang Ying. Fix a bug in region_intersects() for systems with CXL memory.
"mm: hwpoison: two more poison recovery" from Kefeng Wang. Teaches a
couple more code paths to correctly recover from the encountering of
poisoned memry.
"mm: enable large folios swap-in support" from Barry Song. Support the
swapin of mTHP memory into appropriately-sized folios, rather than into
single-page folios.
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Merge tag 'mm-stable-2024-09-20-02-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"Along with the usual shower of singleton patches, notable patch series
in this pull request are:
- "Align kvrealloc() with krealloc()" from Danilo Krummrich. Adds
consistency to the APIs and behaviour of these two core allocation
functions. This also simplifies/enables Rustification.
- "Some cleanups for shmem" from Baolin Wang. No functional changes -
mode code reuse, better function naming, logic simplifications.
- "mm: some small page fault cleanups" from Josef Bacik. No
functional changes - code cleanups only.
- "Various memory tiering fixes" from Zi Yan. A small fix and a
little cleanup.
- "mm/swap: remove boilerplate" from Yu Zhao. Code cleanups and
simplifications and .text shrinkage.
- "Kernel stack usage histogram" from Pasha Tatashin and Shakeel
Butt. This is a feature, it adds new feilds to /proc/vmstat such as
$ grep kstack /proc/vmstat
kstack_1k 3
kstack_2k 188
kstack_4k 11391
kstack_8k 243
kstack_16k 0
which tells us that 11391 processes used 4k of stack while none at
all used 16k. Useful for some system tuning things, but
partivularly useful for "the dynamic kernel stack project".
- "kmemleak: support for percpu memory leak detect" from Pavel
Tikhomirov. Teaches kmemleak to detect leaksage of percpu memory.
- "mm: memcg: page counters optimizations" from Roman Gushchin. "3
independent small optimizations of page counters".
- "mm: split PTE/PMD PT table Kconfig cleanups+clarifications" from
David Hildenbrand. Improves PTE/PMD splitlock detection, makes
powerpc/8xx work correctly by design rather than by accident.
- "mm: remove arch_make_page_accessible()" from David Hildenbrand.
Some folio conversions which make arch_make_page_accessible()
unneeded.
- "mm, memcg: cg2 memory{.swap,}.peak write handlers" fro David
Finkel. Cleans up and fixes our handling of the resetting of the
cgroup/process peak-memory-use detector.
- "Make core VMA operations internal and testable" from Lorenzo
Stoakes. Rationalizaion and encapsulation of the VMA manipulation
APIs. With a view to better enable testing of the VMA functions,
even from a userspace-only harness.
- "mm: zswap: fixes for global shrinker" from Takero Funaki. Fix
issues in the zswap global shrinker, resulting in improved
performance.
- "mm: print the promo watermark in zoneinfo" from Kaiyang Zhao. Fill
in some missing info in /proc/zoneinfo.
- "mm: replace follow_page() by folio_walk" from David Hildenbrand.
Code cleanups and rationalizations (conversion to folio_walk())
resulting in the removal of follow_page().
- "improving dynamic zswap shrinker protection scheme" from Nhat
Pham. Some tuning to improve zswap's dynamic shrinker. Significant
reductions in swapin and improvements in performance are shown.
- "mm: Fix several issues with unaccepted memory" from Kirill
Shutemov. Improvements to the new unaccepted memory feature,
- "mm/mprotect: Fix dax puds" from Peter Xu. Implements mprotect on
DAX PUDs. This was missing, although nobody seems to have notied
yet.
- "Introduce a store type enum for the Maple tree" from Sidhartha
Kumar. Cleanups and modest performance improvements for the maple
tree library code.
- "memcg: further decouple v1 code from v2" from Shakeel Butt. Move
more cgroup v1 remnants away from the v2 memcg code.
- "memcg: initiate deprecation of v1 features" from Shakeel Butt.
Adds various warnings telling users that memcg v1 features are
deprecated.
- "mm: swap: mTHP swap allocator base on swap cluster order" from
Chris Li. Greatly improves the success rate of the mTHP swap
allocation.
- "mm: introduce numa_memblks" from Mike Rapoport. Moves various
disparate per-arch implementations of numa_memblk code into generic
code.
- "mm: batch free swaps for zap_pte_range()" from Barry Song. Greatly
improves the performance of munmap() of swap-filled ptes.
- "support large folio swap-out and swap-in for shmem" from Baolin
Wang. With this series we no longer split shmem large folios into
simgle-page folios when swapping out shmem.
- "mm/hugetlb: alloc/free gigantic folios" from Yu Zhao. Nice
performance improvements and code reductions for gigantic folios.
- "support shmem mTHP collapse" from Baolin Wang. Adds support for
khugepaged's collapsing of shmem mTHP folios.
- "mm: Optimize mseal checks" from Pedro Falcato. Fixes an mprotect()
performance regression due to the addition of mseal().
- "Increase the number of bits available in page_type" from Matthew
Wilcox. Increases the number of bits available in page_type!
- "Simplify the page flags a little" from Matthew Wilcox. Many legacy
page flags are now folio flags, so the page-based flags and their
accessors/mutators can be removed.
- "mm: store zero pages to be swapped out in a bitmap" from Usama
Arif. An optimization which permits us to avoid writing/reading
zero-filled zswap pages to backing store.
- "Avoid MAP_FIXED gap exposure" from Liam Howlett. Fixes a race
window which occurs when a MAP_FIXED operqtion is occurring during
an unrelated vma tree walk.
- "mm: remove vma_merge()" from Lorenzo Stoakes. Major rotorooting of
the vma_merge() functionality, making ot cleaner, more testable and
better tested.
- "misc fixups for DAMON {self,kunit} tests" from SeongJae Park.
Minor fixups of DAMON selftests and kunit tests.
- "mm: memory_hotplug: improve do_migrate_range()" from Kefeng Wang.
Code cleanups and folio conversions.
- "Shmem mTHP controls and stats improvements" from Ryan Roberts.
Cleanups for shmem controls and stats.
- "mm: count the number of anonymous THPs per size" from Barry Song.
Expose additional anon THP stats to userspace for improved tuning.
- "mm: finish isolate/putback_lru_page()" from Kefeng Wang: more
folio conversions and removal of now-unused page-based APIs.
- "replace per-quota region priorities histogram buffer with
per-context one" from SeongJae Park. DAMON histogram
rationalization.
- "Docs/damon: update GitHub repo URLs and maintainer-profile" from
SeongJae Park. DAMON documentation updates.
- "mm/vdpa: correct misuse of non-direct-reclaim __GFP_NOFAIL and
improve related doc and warn" from Jason Wang: fixes usage of page
allocator __GFP_NOFAIL and GFP_ATOMIC flags.
- "mm: split underused THPs" from Yu Zhao. Improve THP=always policy.
This was overprovisioning THPs in sparsely accessed memory areas.
- "zram: introduce custom comp backends API" frm Sergey Senozhatsky.
Add support for zram run-time compression algorithm tuning.
- "mm: Care about shadow stack guard gap when getting an unmapped
area" from Mark Brown. Fix up the various arch_get_unmapped_area()
implementations to better respect guard areas.
- "Improve mem_cgroup_iter()" from Kinsey Ho. Improve the reliability
of mem_cgroup_iter() and various code cleanups.
- "mm: Support huge pfnmaps" from Peter Xu. Extends the usage of huge
pfnmap support.
- "resource: Fix region_intersects() vs add_memory_driver_managed()"
from Huang Ying. Fix a bug in region_intersects() for systems with
CXL memory.
- "mm: hwpoison: two more poison recovery" from Kefeng Wang. Teaches
a couple more code paths to correctly recover from the encountering
of poisoned memry.
- "mm: enable large folios swap-in support" from Barry Song. Support
the swapin of mTHP memory into appropriately-sized folios, rather
than into single-page folios"
* tag 'mm-stable-2024-09-20-02-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (416 commits)
zram: free secondary algorithms names
uprobes: turn xol_area->pages[2] into xol_area->page
uprobes: introduce the global struct vm_special_mapping xol_mapping
Revert "uprobes: use vm_special_mapping close() functionality"
mm: support large folios swap-in for sync io devices
mm: add nr argument in mem_cgroup_swapin_uncharge_swap() helper to support large folios
mm: fix swap_read_folio_zeromap() for large folios with partial zeromap
mm/debug_vm_pgtable: Use pxdp_get() for accessing page table entries
set_memory: add __must_check to generic stubs
mm/vma: return the exact errno in vms_gather_munmap_vmas()
memcg: cleanup with !CONFIG_MEMCG_V1
mm/show_mem.c: report alloc tags in human readable units
mm: support poison recovery from copy_present_page()
mm: support poison recovery from do_cow_fault()
resource, kunit: add test case for region_intersects()
resource: make alloc_free_mem_region() works for iomem_resource
mm: z3fold: deprecate CONFIG_Z3FOLD
vfio/pci: implement huge_fault support
mm/arm64: support large pfn mappings
mm/x86: support large pfn mappings
...
People keep trying to remove three functions that are going to be used in
a feature that is being developed. Dropping the functions entirely may
end up with people trying to use the bit for other uses, as people have
tried in the past.
Adding __maybe_unused stops compilers complaining about the unused
functions so they can be silently optimised out of the compiled code and
people won't try to claim the bit for another use.
Link: https://lore.kernel.org/all/20230726080916.17454-2-zhangpeng.00@bytedance.com/
Link: https://lore.kernel.org/all/202408310728.S7EE59BN-lkp@intel.com/
Link: https://lkml.kernel.org/r/20240907021506.4018676-1-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patch tries to cleanup some function description:
* function name mismatch
* parameter name mismatch
* parameter all end up with ':'
* not prefix '*' if parameter is a pointer
There is still some missing description of parameters, I didn't add them
since I am not sure the exact meaning.
Link: https://lkml.kernel.org/r/20240830220400.2007-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Just do what mt_dump_range64() does.
Dump the error message based on format.
Link: https://lkml.kernel.org/r/20240826012422.29935-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mt_dump_arange64() only applies to an entry whose type is maple_arange_64,
in which mte_is_leaf() must return false.
Since mte_is_leaf() here is always false, we can remove this condition
check.
Link: https://lkml.kernel.org/r/20240826012422.29935-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The return value of various write helper functions are not checked. We
can safely change the return type of these functions to be void.
Link: https://lkml.kernel.org/r/20240814161944.55347-18-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Users of mas_store_prealloc() enter this function with nodes already
preallocated. This means the store type must be already set. We can then
remove the call to mas_wr_store_type() and initialize the write state to
continue the partial walk that was done when determining the store type.
Link: https://lkml.kernel.org/r/20240814161944.55347-17-sidhartha.kumar@oracle.com
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
These sanity checks are now redundant as they are already checked in
mas_wr_store_type(). We can remove them from mas_wr_append() and
mas_wr_node_store().
Link: https://lkml.kernel.org/r/20240814161944.55347-16-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
These write helper functions are all called from store paths which
preallocate enough nodes that will be needed for the write. There is no
more need to allocate within the functions themselves.
Link: https://lkml.kernel.org/r/20240814161944.55347-15-sidhartha.kumar@oracle.com
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
