diff options
author | Qi Zheng | 2023-06-09 08:15:13 +0000 |
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committer | Andrew Morton | 2023-06-19 13:19:33 -0700 |
commit | 07252b0f97150b03050f74f42250f275566d70b9 (patch) | |
tree | 14522e2e4ccce4a49967d754191136f55a515422 /mm/kmemleak.c | |
parent | 47a7c01c3efc6581f5dcca40928baeb38e1e40c2 (diff) |
Revert "mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers()"
This reverts commit 1643db98d9b314e0a592d152603094fbf7ab906e.
Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec
test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make
global slab shrink lockless"). The root cause is that SRCU has to be
careful to not frequently check for SRCU read-side critical section exits.
Therefore, even if no one is currently in the SRCU read-side critical
section, synchronize_srcu() cannot return quickly. That's why
unregister_shrinker() has become slower.
We will try to use the refcount+RCU method [2] proposed by Dave Chinner to
continue to re-implement the lockless slab shrink. So we still need
shrinker_rwsem in synchronize_shrinkers() after reverting the
shrinker_srcu related changes.
[1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/
[2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/
Link: https://lkml.kernel.org/r/20230609081518.3039120-3-qi.zheng@linux.dev
Reported-by: kernel test robot <yujie.liu@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Kirill Tkhai <tkhai@ya.ru>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/kmemleak.c')
0 files changed, 0 insertions, 0 deletions