]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
fs, proc: unconditional cond_resched when reading smaps
authorDavid Rientjes <rientjes@google.com>
Fri, 8 Sep 2017 23:13:41 +0000 (16:13 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 9 Sep 2017 01:26:47 +0000 (18:26 -0700)
commit14038302944a1ceda62a104c137d24a62604d98e
tree94ad493be1d804f812c5fb0729de9afcb8c1d7a5
parent855d97657d4d335970622f0d95ca4966d3f77ee7
fs, proc: unconditional cond_resched when reading smaps

If there are large numbers of hugepages to iterate while reading
/proc/pid/smaps, the page walk never does cond_resched().  On archs
without split pmd locks, there can be significant and observable
contention on mm->page_table_lock which cause lengthy delays without
rescheduling.

Always reschedule in smaps_pte_range() if necessary since the pagewalk
iteration can be expensive.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708211405520.131071@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/proc/task_mmu.c