We recently encountered a bug that makes all zswap store attempt fail.
Specifically, after:
"141fdeececb3 mm/zswap: delay the initialization of zswap"
if we build a kernel with zswap disabled by default, then enabled after
the swapfile is set up, the zswap tree will not be initialized. As a
result, all zswap store calls will be short-circuited. We have to perform
another swapon to get zswap working properly again.
Fortunately, this issue has since been fixed by the patch that kills
frontswap:
"42c06a0e8ebe mm: kill frontswap"
which performs zswap_swapon() unconditionally, i.e always initializing
the zswap tree.
This test add a sanity check that ensure zswap storing works as
intended.
Link: https://lkml.kernel.org/r/20231020222009.2358953-1-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a test to verify that when a memcg hits its limit in zswap, it doesn't
trigger an unwanted writeback that would result in pages not owned by that
memcg to be sent to disk, even if zswap isn't full. This was fixed by
commit 0bdf0efa180a("zswap: do not shrink if cgroup may not zswap").
Link: https://lkml.kernel.org/r/20230621153548.428093-4-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a cgroup selftest that verifies memcg charging in zswap. The original
issue was that kmem bypass was applied to pages swapped out to zswap by
kswapd, resulting in zswapped memory not being charged. It was fixed by
commit cd08d80ecdac("mm: correctly charge compressed memory to its
memcg").
Link: https://lkml.kernel.org/r/20230621153548.428093-3-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "selftests: cgroup: add zswap test program".
This series adds 2 zswap related selftests that verify known and fixed
issues. A new dedicated test program (test_zswap) is proposed since the
test cases are specific to zswap and hosts specific helpers.
The first patch adds the (empty) test program, while the other 2 add an
actual test function each.
This patch (of 3):
Add empty cgroup-zswap self test scaffold program, test functions to be
added in the next commits.
Link: https://lkml.kernel.org/r/20230621153548.428093-1-cerasuolodomenico@gmail.com
Link: https://lkml.kernel.org/r/20230621153548.428093-2-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
