mm: swapoff: take notice of completion sooner
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/[email protected]
Fixes: b56a2d8af914 ("mm: rid swapoff of quadratic complexity")
Signed-off-by: Hugh Dickins <[email protected]>
Cc: "Alex Xu (Hello71)" <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Kelley Nielsen <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Vineeth Pillai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index bf4ef2e..7138362 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2051,11 +2051,9 @@ int try_to_unuse(unsigned int type, bool frontswap,
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 @@ int try_to_unuse(unsigned int type, bool frontswap,
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 @@ int try_to_unuse(unsigned int type, bool frontswap,
* 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;
}
