From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751583AbbIXEV6 (ORCPT ); Thu, 24 Sep 2015 00:21:58 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:33315 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751309AbbIXEVk (ORCPT ); Thu, 24 Sep 2015 00:21:40 -0400 Date: Thu, 24 Sep 2015 13:22:26 +0900 From: Sergey Senozhatsky To: "Kirill A. Shutemov" Cc: Hugh Dickins , Ebru Akagunduz , Sergey Senozhatsky , Michal Hocko , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: Re: [linux-next] khugepaged inconsistent lock state Message-ID: <20150924042225.GB626@swordfish> References: <20150921044600.GA863@swordfish> <20150921150135.GB30755@node.dhcp.inet.fi> <20150923132214.GC25020@node.dhcp.inet.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150923132214.GC25020@node.dhcp.inet.fi> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (09/23/15 16:22), Kirill A. Shutemov wrote: [..] > khugepaged does swap in during collapse under anon_vma lock. It causes > complain from lockdep. The trace below shows following scenario: > > - khugepaged tries to swap in a page under mmap_sem and anon_vma lock; > - do_swap_page() calls swapin_readahead() with GFP_HIGHUSER_MOVABLE; > - __read_swap_cache_async() tries to allocate the page for swap in; > - lockdep_trace_alloc() in __alloc_pages_nodemask() notices that with > given gfp_mask we could end up in direct relaim. > - Lockdep already knows that reclaim sometimes (e.g. in case of > split_huge_page()) wants to take anon_vma lock on its own. > > Therefore deadlock is possible. [..] Gave it some testing on my box. Works fine on my side. I guess you can add (if needed) Tested-by: Sergey Senozhatsky -ss > Signed-off-by: Kirill A. Shutemov > Reported-by: Sergey Senozhatsky > --- > mm/huge_memory.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index dd58ecfcafe6..06c8f6d8fee2 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2725,10 +2725,10 @@ static void collapse_huge_page(struct mm_struct *mm, > goto out; > } > > - anon_vma_lock_write(vma->anon_vma); > - > __collapse_huge_page_swapin(mm, vma, address, pmd); > > + anon_vma_lock_write(vma->anon_vma); > + > pte = pte_offset_map(pmd, address); > pte_ptl = pte_lockptr(mm, pmd); > > -- > Kirill A. Shutemov >