On Tue, Jan 02, 2018 at 02:42:21PM -0800, James Bottomley wrote: > On Tue, 2018-01-02 at 13:22 -0800, Andrew Morton wrote: > > On Fri, 29 Dec 2017 09:55:07 +0900 Minchan Kim <minchan@xxxxxxxxxx> > > wrote: > > > > > > > > James reported a bug of swap paging-in for his testing and found it > > > at rc5, soon to be -rc5. > > > > > > Although we can fix the specific problem at the moment, it may > > > have other lurkig bugs so want to have one more cycle in -next > > > before merging. > > > > > > This patchset reverts 23c47d2ada9f, 08fa93021d80, 8e31f339295f > > > completely > > > but 79b5f08fa34e partially because the swp_swap_info function that > > > 79b5f08fa34e introduced is used by [1]. > > > > Gets a significant reject in do_swap_page(). Could you please take a > > look, redo against current mainline? > > > > Or not. We had a bug and James fixed it. That's what -rc is > > for. Why not fix the thing and proceed? > > My main worry was lack of testing at -rc5, since the bug could > essentially be excited by pushing pages out to swap and then trying to > access them again ... plus since one serious bug was discovered it > wouldn't be unusual for there to be others. However, because of the > IPT stuff, I think Linus is going to take 4.15 over a couple of extra > -rc releases, so this is less of a problem. Then, Here is right fix patch against current mainline. >From 012bdb0774744455ab7aa8abd74c8b9ca1cdc009 Mon Sep 17 00:00:00 2001 From: Minchan Kim <minchan@xxxxxxxxxx> Date: Wed, 3 Jan 2018 08:25:15 +0900 Subject: [PATCH] mm: release locked page in do_swap_page James reported a bug of swap paging-in for his testing. It is that do_swap_page doesn't release locked page so system hang-up happens by deadlock of PG_locked. It was introduced by [1] 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. [1] 0bcac06f27d7, mm, swap: skip swapcache for swapin of synchronous device Link: http://lkml.kernel.org/r/<1514407817.4169.4.camel@xxxxxxxxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Debugged-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> --- mm/memory.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index ca5674cbaff2..793004608332 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
