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3 Commits

Author SHA1 Message Date
Nilay Shroff
74d16965d7 nvmet-loop: avoid using mutex in IO hotpath 
Using mutex lock in IO hot path causes the kernel BUG sleeping while
atomic. Shinichiro[1], first encountered this issue while running blktest
nvme/052 shown below:

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:585
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 996, name: (udev-worker)
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
2 locks held by (udev-worker)/996:
 #0: ffff8881004570c8 (mapping.invalidate_lock){.+.+}-{3:3}, at: page_cache_ra_unbounded+0x155/0x5c0
 #1: ffffffff8607eaa0 (rcu_read_lock){....}-{1:2}, at: blk_mq_flush_plug_list+0xa75/0x1950
CPU: 2 UID: 0 PID: 996 Comm: (udev-worker) Not tainted 6.12.0-rc3+ #339
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x6a/0x90
 __might_resched.cold+0x1f7/0x23d
 ? __pfx___might_resched+0x10/0x10
 ? vsnprintf+0xdeb/0x18f0
 __mutex_lock+0xf4/0x1220
 ? nvmet_subsys_nsid_exists+0xb9/0x150 [nvmet]
 ? __pfx_vsnprintf+0x10/0x10
 ? __pfx___mutex_lock+0x10/0x10
 ? snprintf+0xa5/0xe0
 ? xas_load+0x1ce/0x3f0
 ? nvmet_subsys_nsid_exists+0xb9/0x150 [nvmet]
 nvmet_subsys_nsid_exists+0xb9/0x150 [nvmet]
 ? __pfx_nvmet_subsys_nsid_exists+0x10/0x10 [nvmet]
 nvmet_req_find_ns+0x24e/0x300 [nvmet]
 nvmet_req_init+0x694/0xd40 [nvmet]
 ? blk_mq_start_request+0x11c/0x750
 ? nvme_setup_cmd+0x369/0x990 [nvme_core]
 nvme_loop_queue_rq+0x2a7/0x7a0 [nvme_loop]
 ? __pfx___lock_acquire+0x10/0x10
 ? __pfx_nvme_loop_queue_rq+0x10/0x10 [nvme_loop]
 __blk_mq_issue_directly+0xe2/0x1d0
 ? __pfx___blk_mq_issue_directly+0x10/0x10
 ? blk_mq_request_issue_directly+0xc2/0x140
 blk_mq_plug_issue_direct+0x13f/0x630
 ? lock_acquire+0x2d/0xc0
 ? blk_mq_flush_plug_list+0xa75/0x1950
 blk_mq_flush_plug_list+0xa9d/0x1950
 ? __pfx_blk_mq_flush_plug_list+0x10/0x10
 ? __pfx_mpage_readahead+0x10/0x10
 __blk_flush_plug+0x278/0x4d0
 ? __pfx___blk_flush_plug+0x10/0x10
 ? lock_release+0x460/0x7a0
 blk_finish_plug+0x4e/0x90
 read_pages+0x51b/0xbc0
 ? __pfx_read_pages+0x10/0x10
 ? lock_release+0x460/0x7a0
 page_cache_ra_unbounded+0x326/0x5c0
 force_page_cache_ra+0x1ea/0x2f0
 filemap_get_pages+0x59e/0x17b0
 ? __pfx_filemap_get_pages+0x10/0x10
 ? lock_is_held_type+0xd5/0x130
 ? __pfx___might_resched+0x10/0x10
 ? find_held_lock+0x2d/0x110
 filemap_read+0x317/0xb70
 ? up_write+0x1ba/0x510
 ? __pfx_filemap_read+0x10/0x10
 ? inode_security+0x54/0xf0
 ? selinux_file_permission+0x36d/0x420
 blkdev_read_iter+0x143/0x3b0
 vfs_read+0x6ac/0xa20
 ? __pfx_vfs_read+0x10/0x10
 ? __pfx_vm_mmap_pgoff+0x10/0x10
 ? __pfx___seccomp_filter+0x10/0x10
 ksys_read+0xf7/0x1d0
 ? __pfx_ksys_read+0x10/0x10
 do_syscall_64+0x93/0x180
 ? lockdep_hardirqs_on_prepare+0x16d/0x400
 ? do_syscall_64+0x9f/0x180
 ? lockdep_hardirqs_on+0x78/0x100
 ? do_syscall_64+0x9f/0x180
 ? lockdep_hardirqs_on_prepare+0x16d/0x400
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f565bd1ce11
Code: 00 48 8b 15 09 90 0d 00 f7 d8 64 89 02 b8 ff ff ff ff eb bd e8 d0 ad 01 00 f3 0f 1e fa 80 3d 35 12 0e 00 00 74 13 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 4f c3 66 0f 1f 44 00 00 55 48 89 e5 48 83 ec
RSP: 002b:00007ffd6e7a20c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007f565bd1ce11
RDX: 0000000000001000 RSI: 00007f565babb000 RDI: 0000000000000014
RBP: 00007ffd6e7a2130 R08: 00000000ffffffff R09: 0000000000000000
R10: 0000556000bfa610 R11: 0000000000000246 R12: 000000003ffff000
R13: 0000556000bfa5b0 R14: 0000000000000e00 R15: 0000556000c07328
 </TASK>

Apparently, the above issue is caused due to using mutex lock while
we're in IO hot path. It's a regression caused with commit 505363957f
("nvmet: fix nvme status code when namespace is disabled"). The mutex
->su_mutex is used to find whether a disabled nsid exists in the config
group or not. This is to differentiate between a nsid that is disabled
vs non-existent.

To mitigate the above issue, we've worked upon a fix[2] where we now
insert nsid in subsys Xarray as soon as it's created under config group
and later when that nsid is enabled, we add an Xarray mark on it and set
ns->enabled to true. The Xarray mark is useful while we need to loop
through all enabled namepsaces under a subsystem using xa_for_each_marked()
API. If later a nsid is disabled then we clear Xarray mark from it and also
set ns->enabled to false. It's only when nsid is deleted from the config
group we delete it from the Xarray.

So with this change, now we could easily differentiate a nsid is disabled
(i.e. Xarray entry for ns exists but ns->enabled is set to false) vs non-
existent (i.e.Xarray entry for ns doesn't exist).

Link: https://lore.kernel.org/linux-nvme/20241022070252.GA11389@lst.de/ [2]
Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Closes: https://lore.kernel.org/linux-nvme/tqcy3sveity7p56v7ywp7ssyviwcb3w4623cnxj3knoobfcanq@yxgt2mjkbkam/ [1]
Fixes: 505363957f ("nvmet: fix nvme status code when namespace is disabled")
Fix-suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
 2024-12-27 13:24:00 -08:00
Yu-Chun Lin
41d826c8a9 nvmet: replace kmalloc + memset with kzalloc for data allocation 
cocci warnings: (new ones prefixed by >>)
>> drivers/nvme/target/pr.c:831:8-15: WARNING: kzalloc should be used for data, instead of kmalloc/memset

The pattern of using 'kmalloc' followed by 'memset' is replaced with
'kzalloc', which is functionally equivalent to 'kmalloc' + 'memset',
but more efficient. 'kzalloc' automatically zeroes the allocated
memory, making it a faster and more streamlined solution.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411301434.LEckbcWx-lkp@intel.com/
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yu-Chun Lin <eleanor15x@gmail.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
 2024-12-04 09:20:00 -08:00
Guixin Liu
5a47c2080a nvmet: support reservation feature 
This patch implements the reservation feature, including:
  1. reservation register(register, unregister and replace).
  2. reservation acquire(acquire, preempt, preempt and abort).
  3. reservation release(release and clear).
  4. reservation report.
  5. set feature and get feature of reservation notify mask.
  6. get log page of reservation event.

Not supported:
  1. persistent reservation through power loss.

Test cases:
  Use nvme-cli and fio to test all implemented sub features:
  1. use nvme resv-register to register host a registrant or
     unregister or replace a new key.
  2. use nvme resv-acquire to set host to the holder, and use fio
     to send read and write io in all reservation type. And also
     test preempt and "preempt and abort".
  3. use nvme resv-report to show all registrants and reservation
     status.
  4. use nvme resv-release to release all registrants.
  5. use nvme get-log to get events generated by the preceding
     operations.

In addition, make reservation configurable, one can set ns to
support reservation before enable ns. The default of resv_enable
is false.

Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
 2024-11-11 09:49:48 -08:00