From f80207727aaca3aa34a9cd80659393534de69cad Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 18 Jan 2018 16:33:50 -0800 Subject: [PATCH] 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 0bcac06f27d7 ("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@bbox Signed-off-by: Minchan Kim Reported-by: James Bottomley Acked-by: Hugh Dickins Cc: Sergey Senozhatsky Cc: Huang Ying Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index ca5674c..7930046 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -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); -- 2.7.4