selftests/damon: add a test for the pid leak of dbgfs_target_ids_write()

Commit ebb3f994dd92 ("mm/damon/dbgfs: fix 'struct pid' leaks in
'dbgfs_target_ids_write()'") fixes a pid leak bug in DAMON debugfs
interface, namely dbgfs_target_ids_write() function. Add a selftest for
the issue to prevent the problem from mistakenly recurring.

Link: https://lkml.kernel.org/r/20240207203134.69976-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add a test for a race between target_ids_read() and dbgfs_before_terminate()

commit 34796417964b ("mm/damon/dbgfs: protect targets destructions with
kdamond_lock") fixed a race of DAMON debugfs interface. Specifically, the
race was happening between target_ids_read() and dbgfs_before_terminate().
Add a test for the issue to prevent the problem from accidentally
recurring.

Link: https://lkml.kernel.org/r/20240207203134.69976-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add a test for DAMOS apply intervals

Add a selftest for DAMOS apply intervals. It runs two schemes having
different apply interval agains an artificial memory access workload, and
check if the scheme with smaller apply interval was applied more
frequently.

Link: https://lkml.kernel.org/r/20240207203134.69976-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add a test for DAMOS quota

Add a selftest for verifying the DAMOS quota feature. The test is very
similar to sysfs_update_schemes_tried_regions_wss_estimation.py. It
starts an artificial workload of 20 MiB working set, run DAMON to find the
working set size, but with 1 MiB/100 ms size quota. Then, it collect the
DAMON-found working set size every 100 ms and check if the quota was
always applied as expected. For the confirmation, the tests shows the
stat-applied region size and the qt_exceeds stat.

Link: https://lkml.kernel.org/r/20240207203134.69976-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add a test for update_schemes_tried_regions hang bug

Add a test for reproducing the update_schemes_tried_{regions,bytes}
command-causing indefinite hang bug that fixed by commit 7d6fa31a2fd7
("mm/damon/sysfs-schemes: add timeout for update_schemes_tried_regions"),
to avoid mistakenly re-introducing the bug. Refer to the fix commit for
more details of the bug.

Link: https://lkml.kernel.org/r/20231212194810.54457-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add a test for update_schemes_tried_regions sysfs command

Add a selftest for verifying the accuracy of DAMON's access monitoring
functionality. The test starts a program of artificial access pattern,
monitor the access pattern using DAMON, and check if DAMON finds expected
amount of hot data region (working set size) with only acceptable error
rate.

Note that the acceptable error rate is set with only naive assumptions and
small number of tests. Hence failures of the test may not always mean
DAMON is broken. Rather than that, those could be a signal to better
understand the real accuracy level of DAMON in wider environments. Based
on further finding, we could optimize DAMON or adjust the expectation of
the test.

Link: https://lkml.kernel.org/r/20231212194810.54457-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: test removed scheme sysfs dir access bug

A DAMON sysfs user could start DAMON with a scheme, remove the sysfs
directory for the scheme, and then ask stats or schemes tried regions
update. The related logic were not aware of the already removed directory
situation, so it was able to results in invalid memory accesses. The fix
has made with commit 8468b486612c ("mm/damon/sysfs-schemes: skip stats
update if the scheme directory is removed"), though. Add a selftest to
prevent such kinds of bugs from being introduced again.

Link: https://lkml.kernel.org/r/20221201170834.62823-1-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: test non-context inputs to rm_contexts file

There was a bug[1] that triggered by writing non-context DAMON debugfs
file names to the 'rm_contexts' DAMON debugfs file. Add a selftest for
the bug to avoid it happen again.

[1] https://lore.kernel.org/damon/000000000000ede3ac05ec4abf8e@google.com/

Link: https://lkml.kernel.org/r/20221107165001.5717-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add tests for DAMON_LRU_SORT's enabled parameter

Add simple test cases for DAMON_LRU_SORT's 'enabled' parameter. Those
tests are focusing on the synchronous behavior of DAMON_RECLAIM enabling
and disabling.

Link: https://lkml.kernel.org/r/20221025173650.90624-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add tests for DAMON_RECLAIM's enabled parameter

Add simple test cases for DAMON_RECLAIM's 'enabled' parameter. Those
tests are focusing on the synchronous behavior of DAMON_RECLAIM enabling
and disabling.

Link: https://lkml.kernel.org/r/20221025173650.90624-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftest/damon: add a test for duplicate context dirs creation

Patch series "mm/damon: minor fixes and cleanups".

This patchset contains minor fixes and cleanups for DAMON including

- selftest for a bug we found before (Patch 1),
- fix of region holes in vaddr corner case and a kunit test for it
(Patches 2 and 3), and
- documents/Kconfig updates for title wordsmithing (Patch 4) and more
aggressive DAMON debugfs interface deprecation announcement
(Patches 5-7).


This patch (of 7):

Commit d26f60703606 ("mm/damon/dbgfs: avoid duplicate context directory
creation") fixes a bug which could result in memory leak and DAMON
disablement. This commit adds a selftest for verifying the fix and avoid
regression.

Link: https://lkml.kernel.org/r/20220909202901.57977-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20220909202901.57977-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yun Levi <ppbuk5246@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/damon: add a test for DAMON sysfs interface

This commit adds a selftest for DAMON sysfs interface. It tests the
functionality of 'nr' files and existence of files in each directory of
the hierarchy.

Link: https://lkml.kernel.org/r/20220228081314.5770-12-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

selftests/damon: split test cases

Currently, the single test program, debugfs.sh, contains all test cases
for DAMON. When one of the cases fails, finding which case is failed
from the test log is not so easy, and all remaining tests will be
skipped. To improve the situation, this commit splits the single
program into small test programs having their own names.

Link: https://lkml.kernel.org/r/20211201150440.1088-12-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

selftests/damon: test debugfs file reads/writes with huge count

DAMON debugfs interface users were able to trigger warning by writing
some files with arbitrarily large 'count' parameter. The issue is fixed
with commit db7a347b26fe ("mm/damon/dbgfs: use '__GFP_NOWARN' for
user-specified size buffer allocation"). This commit adds a test case
for the issue in DAMON selftests to avoid future regressions.

Link: https://lkml.kernel.org/r/20211201150440.1088-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/damon: add user space selftests

This commit adds a simple user space tests for DAMON. The tests are using
kselftest framework.

Link: https://lkml.kernel.org/r/20210716081449.22187-13-sj38.park@gmail.com
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Markus Boehme <markubo@amazon.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David Woodhouse <dwmw@amazon.com>
Cc: Fan Du <fan.du@intel.com>
Cc: Fernand Sieber <sieberf@amazon.com>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leonard Foerster <foersleo@amazon.de>
Cc: Marco Elver <elver@google.com>
Cc: Maximilian Heyne <mheyne@amazon.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>