From: Hugh Dickins hughd@google.com

commit a66c0410b97c07a5708881198528ce724f7a3226 upstream.

The other pagetable walks in task_mmu.c have a cond_resched() after walking their ptes: add a cond_resched() in gather_pte_stats() too, for reading /proc/<id>/numa_maps. Only pagemap_pmd_range() has a cond_resched() in its (unusually expensive) pmd_trans_huge case: more should probably be added, but leave them unchanged for now.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052157400.13021@eggly.anvils Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Michal Hocko mhocko@suse.com Cc: David Rientjes rientjes@google.com Cc: Gerald Schaefer gerald.schaefer@de.ibm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Cc: stable@vger.kernel.org # 4.9.x Reported-by: Chen si cici.cs@alibaba-inc.com Signed-off-by: Baoyou Xie baoyou.xie@aliyun.com Signed-off-by: Wen Yang wenyang@linux.alibaba.org Signed-off-by: Zijiang Huang zijiang.hzj@alibaba-inc.com --- fs/proc/task_mmu.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 4b207b1..e6c8ead 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1609,6 +1609,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,

} while (pte++, addr += PAGE_SIZE, addr != end); pte_unmap_unlock(orig_pte, ptl); + cond_resched(); return 0; } #ifdef CONFIG_HUGETLB_PAGE