shmem: use raw_spinlock_t for ->stat_lock

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Each CPU has SHMEM_INO_BATCH inodes available in `->ino_batch' which is
per-CPU.  Access here is serialized by disabling preemption.  If the pool
is empty, it gets reloaded from `->next_ino'.  Access here is serialized
by ->stat_lock which is a spinlock_t and can not be acquired with disabled
preemption.

One way around it would make per-CPU ino_batch struct containing the inode
number a local_lock_t.

Another solution is to promote ->stat_lock to a raw_spinlock_t.  The
critical sections are short.  The mpol_put() must be moved outside of the
critical section to avoid invoking the destructor with disabled
preemption.

Link: https://lkml.kernel.org/r/20210806142916.jdwkb5bx62q5fwfo@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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Sebastian Andrzej Siewior 2021-09-02 14:54:03 -07:00 • committed by Linus Torvalds

parent 3969b1a654

commit bf11b9a8e9

2 changed files with 18 additions and 15 deletions

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2

include/linux/shmem_fs.h

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31

mm/shmem.c

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