mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-27 04:47:05 +00:00
mm/page_alloc.c: do not acquire zone lock in is_free_buddy_page()
Grabbing zone lock in is_free_buddy_page() gives a wrong sense of safety, and has potential performance implications when zone is experiencing lock contention. In any case, if a caller needs a stable result, it should grab zone lock before calling this function. Link: https://lkml.kernel.org/r/20210922152833.4023972-1-eric.dumazet@gmail.com Signed-off-by: Eric Dumazet <edumazet@google.com> 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>
This commit is contained in:
parent
ebeac3ea99
commit
8446b59baa
1 changed files with 5 additions and 5 deletions
|
@ -9356,21 +9356,21 @@ void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
|
|||
}
|
||||
#endif
|
||||
|
||||
/*
|
||||
* This function returns a stable result only if called under zone lock.
|
||||
*/
|
||||
bool is_free_buddy_page(struct page *page)
|
||||
{
|
||||
struct zone *zone = page_zone(page);
|
||||
unsigned long pfn = page_to_pfn(page);
|
||||
unsigned long flags;
|
||||
unsigned int order;
|
||||
|
||||
spin_lock_irqsave(&zone->lock, flags);
|
||||
for (order = 0; order < MAX_ORDER; order++) {
|
||||
struct page *page_head = page - (pfn & ((1 << order) - 1));
|
||||
|
||||
if (PageBuddy(page_head) && buddy_order(page_head) >= order)
|
||||
if (PageBuddy(page_head) &&
|
||||
buddy_order_unsafe(page_head) >= order)
|
||||
break;
|
||||
}
|
||||
spin_unlock_irqrestore(&zone->lock, flags);
|
||||
|
||||
return order < MAX_ORDER;
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue