From 1e4b6a92864e933a53e1ad1986350f71ee6b530a Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 18 Apr 2019 17:50:09 -0700 Subject: [PATCH] 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/alpine.LSU.2.11.1904081258200.1523@eggly.anvils Fixes: e4b318d7e2c0 ("mm: rid swapoff of quadratic complexity") Signed-off-by: Hugh Dickins Cc: "Alex Xu (Hello71)" Cc: Huang Ying Cc: Kelley Nielsen Cc: Konstantin Khlebnikov Cc: Rik van Riel Cc: Vineeth Pillai Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swapfile.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index bf4ef2e40f23d..71383625a582c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -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; } -- 2.39.5