linux.git/mm/damon, branch v5.19 Linux kernel source tree mm/damon: use set_huge_pte_at() to make huge pte old 2022-07-03T22:42:32+00:00 Baolin Wang baolin.wang@linux.alibaba.com 2022-06-20T02:34:42+00:00 ed1523a895ffdabcab6e067af18685ed00f5ce15 The huge_ptep_set_access_flags() can not make the huge pte old according to the discussion [1], that means we will always mornitor the young state of the hugetlb though we stopped accessing the hugetlb, as a result DAMON will get inaccurate accessing statistics. So changing to use set_huge_pte_at() to make the huge pte old to fix this issue. [1] https://lore.kernel.org/all/Yqy97gXI4Nqb7dYo@arm.com/ Link: https://lkml.kernel.org/r/1655692482-28797-1-git-send-email-baolin.wang@linux.alibaba.com Fixes: 49f4203aae06 ("mm/damon: add access checking for hugetlb pages") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: SeongJae Park <sj@kernel.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
The huge_ptep_set_access_flags() can not make the huge pte old according
to the discussion [1], that means we will always mornitor the young state
of the hugetlb though we stopped accessing the hugetlb, as a result DAMON
will get inaccurate accessing statistics.

So changing to use set_huge_pte_at() to make the huge pte old to fix this
issue.

[1] https://lore.kernel.org/all/Yqy97gXI4Nqb7dYo@arm.com/

Link: https://lkml.kernel.org/r/1655692482-28797-1-git-send-email-baolin.wang@linux.alibaba.com
Fixes: 49f4203aae06 ("mm/damon: add access checking for hugetlb pages")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/reclaim: schedule 'damon_reclaim_timer' only after 'system_wq' is initialized 2022-06-17T02:11:30+00:00 SeongJae Park sj@kernel.org 2022-06-04T19:50:51+00:00 2949282938135ab734c3829495ae393523ceb702 Commit 059342d1dd4e ("mm/damon/reclaim: fix the timer always stays active") made DAMON_RECLAIM's 'enabled' parameter store callback, 'enabled_store()', to schedule 'damon_reclaim_timer'. The scheduling uses 'system_wq', which is initialized in 'workqueue_init_early()'. As kernel parameters parsing function ('parse_args()') is called before 'workqueue_init_early()', 'enabled_store()' can be executed before 'workqueue_init_early()' and end up accessing the uninitialized 'system_wq'. As a result, the booting hang[1]. This commit fixes the issue by checking if the initialization is done before scheduling the timer. [1] https://lkml.kernel.org/20220604192222.1488-1-sj@kernel.org/ Link: https://lkml.kernel.org/r/20220604195051.1589-1-sj@kernel.org Fixes: 059342d1dd4e ("mm/damon/reclaim: fix the timer always stays active") Signed-off-by: SeongJae Park <sj@kernel.org> Reported-by: Greg White <gwhite@kupulau.com> Cc: Hailong Tu <tuhailong@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Commit 059342d1dd4e ("mm/damon/reclaim: fix the timer always stays
active") made DAMON_RECLAIM's 'enabled' parameter store callback,
'enabled_store()', to schedule 'damon_reclaim_timer'.  The scheduling uses
'system_wq', which is initialized in 'workqueue_init_early()'.  As kernel
parameters parsing function ('parse_args()') is called before
'workqueue_init_early()', 'enabled_store()' can be executed before
'workqueue_init_early()' and end up accessing the uninitialized
'system_wq'.  As a result, the booting hang[1].  This commit fixes the
issue by checking if the initialization is done before scheduling the
timer.

[1] https://lkml.kernel.org/20220604192222.1488-1-sj@kernel.org/

Link: https://lkml.kernel.org/r/20220604195051.1589-1-sj@kernel.org
Fixes: 059342d1dd4e ("mm/damon/reclaim: fix the timer always stays active")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Greg White <gwhite@kupulau.com>
Cc: Hailong Tu <tuhailong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: damon: use HPAGE_PMD_SIZE 2022-05-19T21:08:55+00:00 Kefeng Wang wangkefeng.wang@huawei.com 2022-05-17T14:51:20+00:00 02e34fff195d3a5f67cbb553795dc109a37d1dcf Use HPAGE_PMD_SIZE instead of open coding. Link: https://lkml.kernel.org/r/20220517145120.118523-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Use HPAGE_PMD_SIZE instead of open coding.

Link: https://lkml.kernel.org/r/20220517145120.118523-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/reclaim: use resource_size function on resource object 2022-05-13T14:20:18+00:00 Jiapeng Chong jiapeng.chong@linux.alibaba.com 2022-05-13T03:23:07+00:00 2e14a8d3bbccf22a807c012ff6e7c2f307600e4a Fix the following coccicheck warnings: ./mm/damon/reclaim.c:241:30-33: WARNING: Suspicious code. resource_size is maybe missing with res. Link: https://lkml.kernel.org/r/20220507032512.129598-1-jiapeng.chong@linux.alibaba.com Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Reported-by: Abaci Robot <abaci@linux.alibaba.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: "Boehme, Markus" <markubo@amazon.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Fix the following coccicheck warnings:

./mm/damon/reclaim.c:241:30-33: WARNING: Suspicious code. resource_size is maybe missing with res.

Link: https://lkml.kernel.org/r/20220507032512.129598-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: "Boehme, Markus" <markubo@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/reclaim: support online inputs update 2022-05-13T14:20:09+00:00 SeongJae Park sj@kernel.org 2022-05-10T01:20:56+00:00 e035c280f6dfebf0cf7462a03d83294ca1b8c4e3 DAMON_RECLAIM reads the user input parameters only when it starts. To allow more efficient online tuning, this commit implements a new input parameter called 'commit_inputs'. Writing true to the parameter makes DAMON_RECLAIM reads the input parameters again. Link: https://lkml.kernel.org/r/20220429160606.127307-14-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
DAMON_RECLAIM reads the user input parameters only when it starts.  To
allow more efficient online tuning, this commit implements a new input
parameter called 'commit_inputs'.  Writing true to the parameter makes
DAMON_RECLAIM reads the input parameters again.

Link: https://lkml.kernel.org/r/20220429160606.127307-14-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/sysfs: support online inputs update 2022-05-13T14:20:09+00:00 SeongJae Park sj@kernel.org 2022-05-10T01:20:56+00:00 da87878010e59869d4d27b3c01ecc8ec06ff4a20 Currently, DAMON sysfs interface doesn't provide a way for adjusting DAMON input parameters while it is turned on. Therefore, users who want to reconfigure DAMON need to stop DAMON and restart. This means all the monitoring results that accumulated so far, which could be useful, should be flushed. This would be inefficient for many cases. For an example, let's suppose a sysadmin was running a DAMON-based Operation Scheme to find memory regions not accessed for more than 5 mins and page out the regions. If it turns out the 5 mins threshold was too long and therefore the sysadmin wants to reduce it to 4 mins, the sysadmin should turn off DAMON, restart it, and wait for at least 4 more minutes so that DAMON can find the cold memory regions, even though DAMON was knowing there are regions that not accessed for 4 mins at the time of shutdown. This commit makes DAMON sysfs interface to support online DAMON input parameters updates by adding a new input keyword for the 'state' DAMON sysfs file, 'commit'. Writing the keyword to the 'state' file while the corresponding kdamond is running makes the kdamond to read the sysfs file values again and update the DAMON context. Link: https://lkml.kernel.org/r/20220429160606.127307-12-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Currently, DAMON sysfs interface doesn't provide a way for adjusting DAMON
input parameters while it is turned on.  Therefore, users who want to
reconfigure DAMON need to stop DAMON and restart.  This means all the
monitoring results that accumulated so far, which could be useful, should
be flushed.  This would be inefficient for many cases.

For an example, let's suppose a sysadmin was running a DAMON-based
Operation Scheme to find memory regions not accessed for more than 5 mins
and page out the regions.  If it turns out the 5 mins threshold was too
long and therefore the sysadmin wants to reduce it to 4 mins, the sysadmin
should turn off DAMON, restart it, and wait for at least 4 more minutes so
that DAMON can find the cold memory regions, even though DAMON was knowing
there are regions that not accessed for 4 mins at the time of shutdown.

This commit makes DAMON sysfs interface to support online DAMON input
parameters updates by adding a new input keyword for the 'state' DAMON
sysfs file, 'commit'.  Writing the keyword to the 'state' file while the
corresponding kdamond is running makes the kdamond to read the sysfs file
values again and update the DAMON context.

Link: https://lkml.kernel.org/r/20220429160606.127307-12-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/sysfs: update schemes stat in the kdamond context 2022-05-13T14:20:09+00:00 SeongJae Park sj@kernel.org 2022-05-10T01:20:56+00:00 01538719c098f51ac0742ef610d127ba3e3d1e03 Only '->kdamond' and '->kdamond_stop' are protected by 'kdamond_lock' of 'struct damon_ctx'. All other DAMON context internal data items are recommended to be accessed in DAMON callbacks, or under some additional synchronizations. But, DAMON sysfs is accessing the schemes stat under 'kdamond_lock'. It makes no big issue as the read values are not used anywhere inside kernel, but would better to be fixed. This commit moves the reads to DAMON callback context, as supposed to be used for the purpose. Link: https://lkml.kernel.org/r/20220429160606.127307-11-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Only '->kdamond' and '->kdamond_stop' are protected by 'kdamond_lock' of
'struct damon_ctx'.  All other DAMON context internal data items are
recommended to be accessed in DAMON callbacks, or under some additional
synchronizations.  But, DAMON sysfs is accessing the schemes stat under
'kdamond_lock'.

It makes no big issue as the read values are not used anywhere inside
kernel, but would better to be fixed.  This commit moves the reads to
DAMON callback context, as supposed to be used for the purpose.

Link: https://lkml.kernel.org/r/20220429160606.127307-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/sysfs: use enum for 'state' input handling 2022-05-13T14:20:08+00:00 SeongJae Park sj@kernel.org 2022-05-10T01:20:55+00:00 3cbab4ca1ea8752912d8719d72059869b4c18045 DAMON sysfs 'state' file handling code is using string literals in both 'state_show()' and 'state_store()'. This makes the code error prone and inflexible for future extensions. To improve the situation, this commit defines possible input strings and 'enum' for identifying each input keyword only once, and refactors the code to reuse those. Link: https://lkml.kernel.org/r/20220429160606.127307-10-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
DAMON sysfs 'state' file handling code is using string literals in both
'state_show()' and 'state_store()'.  This makes the code error prone and
inflexible for future extensions.

To improve the situation, this commit defines possible input strings and
'enum' for identifying each input keyword only once, and refactors the
code to reuse those.

Link: https://lkml.kernel.org/r/20220429160606.127307-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/sysfs: reuse damon_set_regions() for regions setting 2022-05-13T14:20:08+00:00 SeongJae Park sj@kernel.org 2022-05-10T01:20:55+00:00 97d482f4592fde2322c319f07bc54f3a0d37861c 'damon_set_regions()' is general enough so that it can also be used for only creating regions. This commit makes DAMON sysfs interface to reuse the function rather keeping two implementations for a same purpose. Link: https://lkml.kernel.org/r/20220429160606.127307-9-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
'damon_set_regions()' is general enough so that it can also be used for
only creating regions.  This commit makes DAMON sysfs interface to reuse
the function rather keeping two implementations for a same purpose.

Link: https://lkml.kernel.org/r/20220429160606.127307-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/damon/sysfs: move targets setup code to a separated function 2022-05-13T14:20:08+00:00 SeongJae Park sj@kernel.org 2022-05-10T01:20:55+00:00 74bd8b7d2f8e7014dc34d6c5f51c629afdf822cb This commit separates DAMON sysfs interface's monitoring context targets setup code to a new function for better readability. Link: https://lkml.kernel.org/r/20220429160606.127307-8-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
This commit separates DAMON sysfs interface's monitoring context targets
setup code to a new function for better readability.

Link: https://lkml.kernel.org/r/20220429160606.127307-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>