Re: [PATCH 2/3] mm: cond_resched in scan_mapping_unevictable_pages
From: KOSAKI Motohiro <hidden>
Date: 2011-12-29 05:14:30
(12/28/11 11:36 PM), Hugh Dickins wrote:
quoted hunk ↗ jump to hunk
scan_mapping_unevictable_pages() is used to make SysV SHM_LOCKed pages evictable again once the shared memory is unlocked or destroyed (the latter seems rather a waste of time, but meets internal expectations). It does pagevec_lookup()s across the whole object: methinks a cond_resched() every PAGEVEC_SIZE pages would be worthwhile. Signed-off-by: Hugh Dickins<hughd@google.com> --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)--- mmotm.orig/mm/vmscan.c 2011-12-28 16:49:36.000000000 -0800 +++ mmotm/mm/vmscan.c 2011-12-28 17:03:07.647220248 -0800@@ -3583,8 +3583,8 @@ void scan_mapping_unevictable_pages(stru pagevec_release(&pvec); count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); + cond_resched(); }
Hmm...
scan_mapping_unevictable_pages() is always under spinlock?
int shmem_lock(struct file *file, int lock, struct user_struct *user)
{
spin_lock(&info->lock);
(snip)
smp_mb__after_clear_bit();
scan_mapping_unevictable_pages(file->f_mapping);
(snip)
out_nomem:
spin_unlock(&info->lock);
return retval;
}
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