mm/vmalloc: Fix unlock order in s_stop()
When multiple locks are acquired, they should be released in reverse order. For s_start() and s_stop() in mm/vmalloc.c, that is not the case. s_start: mutex_lock(&vmap_purge_lock); spin_lock(&vmap_area_lock); s_stop : mutex_unlock(&vmap_purge_lock); spin_unlock(&vmap_area_lock); This unlock sequence, though allowed, is not optimal. If a waiter is present, mutex_unlock() will need to go through the slowpath of waking up the waiter with preemption disabled. Fix that by releasing the spinlock first before the mutex. Link: https://lkml.kernel.org/r/20201213180843.16938-1-longman@redhat.com Fixes: e36176be ("mm/vmalloc: rework vmap_area_lock") Signed-off-by:Waiman Long <longman@redhat.com> Reviewed-by:
Uladzislau Rezki (Sony) <urezki@gmail.com> Reviewed-by:
David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
parent
e924d461
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