Files
android_kernel_xiaomi_sm8450/include/linux
Chinwen Chang 07e5bfe651 mmap locking API: add mmap_lock_is_contended()
Patch series "Try to release mmap_lock temporarily in smaps_rollup", v4.

Recently, we have observed some janky issues caused by unpleasantly long
contention on mmap_lock which is held by smaps_rollup when probing large
processes.  To address the problem, we let smaps_rollup detect if anyone
wants to acquire mmap_lock for write attempts.  If yes, just release the
lock temporarily to ease the contention.

smaps_rollup is a procfs interface which allows users to summarize the
process's memory usage without the overhead of seq_* calls.  Android uses
it to sample the memory usage of various processes to balance its memory
pool sizes.  If no one wants to take the lock for write requests,
smaps_rollup with this patch will behave like the original one.

Although there are on-going mmap_lock optimizations like range-based
locks, the lock applied to smaps_rollup would be the coarse one, which is
hard to avoid the occurrence of aforementioned issues.  So the detection
and temporary release for write attempts on mmap_lock in smaps_rollup is
still necessary.

This patch (of 3):

Add new API to query if someone wants to acquire mmap_lock for write
attempts.

Using this instead of rwsem_is_contended makes it more tolerant of future
changes to the lock type.

Signed-off-by: Chinwen Chang <chinwen.chang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Michel Lespinasse <walken@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Daniel Kiss <daniel.kiss@arm.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jimmy Assarsson <jimmyassarsson@gmail.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/1597715898-3854-1-git-send-email-chinwen.chang@mediatek.com
Link: http://lkml.kernel.org/r/1597715898-3854-2-git-send-email-chinwen.chang@mediatek.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-13 18:38:31 -07:00
..
2020-08-03 18:19:23 -07:00
2020-06-25 22:25:13 -07:00
2020-06-16 14:19:57 +02:00
2020-07-27 14:55:22 +01:00
2020-10-13 18:38:27 -07:00
2020-05-24 20:48:11 +02:00
2020-07-21 08:24:52 -05:00
2020-07-08 10:48:35 -07:00
2020-07-21 13:26:26 -07:00
2020-06-24 17:08:31 +02:00
2020-06-16 19:25:20 +02:00
2020-07-27 14:29:23 -04:00
2020-05-04 11:19:58 -07:00
2020-06-17 00:07:38 +02:00
2020-08-14 19:56:56 -07:00
2020-07-24 17:12:41 -07:00
2020-04-30 12:54:01 -07:00
2020-08-04 21:02:38 -04:00
2020-07-24 17:12:41 -07:00
2020-05-18 10:30:21 +01:00
2020-08-26 12:41:56 +02:00
2020-06-02 15:15:46 +01:00
2020-09-04 09:25:20 -07:00
2020-05-08 18:18:11 +01:00
2020-05-08 00:12:42 +02:00
2020-05-28 10:31:09 +02:00
2020-10-13 18:38:31 -07:00
2020-09-04 12:46:07 +01:00
2020-05-09 13:57:12 +02:00
2020-07-01 10:49:02 +02:00
2020-07-23 17:34:18 +10:00
2020-09-04 12:46:06 +01:00
2020-10-13 18:38:29 -07:00
2020-05-15 13:51:28 -07:00
2020-05-09 13:57:12 +02:00
2020-08-18 17:06:15 +02:00
2020-07-16 23:19:51 +02:00
2020-08-07 11:33:24 -07:00
2020-05-17 14:10:07 -06:00
2020-05-14 16:44:24 +02:00
2020-05-04 09:16:37 -07:00
2020-07-04 09:35:36 -05:00
2020-07-07 11:58:59 -05:00
2020-08-01 11:28:17 +02:00
2020-06-26 00:27:38 -07:00