selftests: damon: add access_memory to .gitignore

This binary is missing in the .gitignore and stays as an untracked file.

Link: https://lore.kernel.org/r/20240214-damon_selftest_gitignore-v1-1-f517d0f9f783@gmail.com
Link: https://lkml.kernel.org/r/20240221211148.46522-3-sj@kernel.org
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Singed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Closes: https://lore.kernel.org/all/AS8P193MB1285C963658008F1B2702AF7E4792@AS8P193MB1285.EURP193.PROD.OUTLOOK.COM/
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Vincenzo Mezzela <vincenzo.mezzela@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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: 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>