Commit f8020772 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds

mm/memory.c: release locked page in do_swap_page()

James reported a bug in swap paging-in from his testing.  It is that
do_swap_page doesn't release locked page so system hang-up happens due
to a deadlock on PG_locked.

It was introduced by 0bcac06f ("mm, swap: skip swapcache for swapin
of synchronous device") because I missed swap cache hit places to update
swapcache variable to work well with other logics against swapcache in
do_swap_page.

This patch fixes it.

Debugged by James Bottomley.

Link: http://lkml.kernel.org/r/<1514407817.4169.4.camel@HansenPartnership.com>
Link: http://lkml.kernel.org/r/20180102235606.GA19438@bboxSigned-off-by: default avatarMinchan Kim <minchan@kernel.org>
Reported-by: default avatarJames Bottomley <James.Bottomley@hansenpartnership.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dda3e152
......@@ -2857,8 +2857,11 @@ int do_swap_page(struct vm_fault *vmf)
int ret = 0;
bool vma_readahead = swap_use_vma_readahead();
if (vma_readahead)
if (vma_readahead) {
page = swap_readahead_detect(vmf, &swap_ra);
swapcache = page;
}
if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) {
if (page)
put_page(page);
......@@ -2889,9 +2892,12 @@ int do_swap_page(struct vm_fault *vmf)
delayacct_set_flag(DELAYACCT_PF_SWAPIN);
if (!page)
if (!page) {
page = lookup_swap_cache(entry, vma_readahead ? vma : NULL,
vmf->address);
swapcache = page;
}
if (!page) {
struct swap_info_struct *si = swp_swap_info(entry);
......
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