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mm: swapoff: take notice of completion sooner

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The old try_to_unuse() implementation was driven by find_next_to_unuse(),
which terminated as soon as all the swap had been freed.

Add inuse_pages checks now (alongside signal_pending()) to stop scanning
mms and swap_map once finished.

The same ought to be done in shmem_unuse() too, but never was before,
and needs a different interface: so leave it as is for now.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1904081258200.1523@eggly.anvils
Fixes: b56a2d8af914 ("mm: rid swapoff of quadratic complexity")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Kelley Nielsen <kelleynnn@gmail.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vineeth Pillai <vpillai@digitalocean.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2019-04-18 17:50:09 -07:00 committed by Linus Torvalds
parent dd862deb15
commit 64165b1aff
1 changed files with 11 additions and 8 deletions
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19
mm/swapfile.c
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@ -2051,11 +2051,9 @@ retry:
spin_lock(&mmlist_lock);
p = &init_mm.mmlist;
while ((p = p->next) != &init_mm.mmlist) {
if (signal_pending(current)) {
retval = -EINTR;
break;
}
while (si->inuse_pages &&
!signal_pending(current) &&
(p = p->next) != &init_mm.mmlist) {
mm = list_entry(p, struct mm_struct, mmlist);
if (!mmget_not_zero(mm))
@ -2082,7 +2080,9 @@ retry:
mmput(prev_mm);
i = 0;
while ((i = find_next_to_unuse(si, i, frontswap)) != 0) {
while (si->inuse_pages &&
!signal_pending(current) &&
(i = find_next_to_unuse(si, i, frontswap)) != 0) {
entry = swp_entry(type, i);
page = find_get_page(swap_address_space(entry), i);
@ -2123,8 +2123,11 @@ retry:
* separate lists, and wait for those lists to be emptied; but it's
* easier and more robust (though cpu-intensive) just to keep retrying.
*/
if (si->inuse_pages)
goto retry;
if (si->inuse_pages) {
if (!signal_pending(current))
goto retry;
retval = -EINTR;
}
out:
return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval;
}