From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: Re: mm: kernel BUG at mm/huge_memory.c:1371! Date: Thu, 10 Apr 2014 13:37:27 +0300 Message-ID: <20140410103727.GA24354@node.dhcp.inet.fi> References: <5307D74C.5070002@oracle.com> <20140221235145.GA18046@node.dhcp.inet.fi> <5307F90C.9060602@oracle.com> <5310C56C.60709@oracle.com> <53446261.9070903@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <53446261.9070903@oracle.com> Sender: linux-kernel-owner@vger.kernel.org To: Sasha Levin Cc: "linux-mm@kvack.org" , Andrew Morton , LKML List-Id: linux-mm.kvack.org On Tue, Apr 08, 2014 at 04:56:01PM -0400, Sasha Levin wrote: > On 02/28/2014 12:20 PM, Sasha Levin wrote: > > On 02/21/2014 08:10 PM, Sasha Levin wrote: > >> On 02/21/2014 06:51 PM, Kirill A. Shutemov wrote: > >>> On Fri, Feb 21, 2014 at 05:46:36PM -0500, Sasha Levin wrote: > >>>> >Hi all, > >>>> > > >>>> >While fuzzing with trinity inside a KVM tools guest running latest -next > >>>> >kernel I've stumbled on the following (now with pretty line numbers!) spew: > >>>> > > >>>> >[ 746.125099] kernel BUG at mm/huge_memory.c:1371! > >>> It "VM_BUG_ON_PAGE(!PageHead(page), page);", correct? > >>> I don't see dump_page() output. > >> > >> Right. However, I'm not seeing the dump_page() output in the log. > >> > >> I see that dump_page() has been modified not long ago, I'm looking into it. > > > > Alright, here we go: > > > > [ 3323.062742] page:ffffea00080f0000 count:3 mapcount:0 mapping:ffff8802292ee0e1 index:0x7fa2e6800 > > [ 3323.065978] page flags: 0x16fffff80090018(uptodate|dirty|swapcache|swapbacked) > > [ 3323.068535] ------------[ cut here ]------------ > > [ 3323.069669] kernel BUG at mm/huge_memory.c:1371! > > [ 3323.070961] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > > [ 3323.071028] Dumping ftrace buffer: > > [ 3323.071028] (ftrace buffer empty) > > [ 3323.071028] Modules linked in: > > [ 3323.071028] CPU: 101 PID: 48284 Comm: trinity-c101 Tainted: G W 3.14.0-rc4-next-20140228-sasha-00011-g4077c67 #25 > > [ 3323.071028] task: ffff8800c2718000 ti: ffff8800c26ec000 task.ti: ffff8800c26ec000 > > [ 3323.071028] RIP: 0010:[] [] zap_huge_pmd+0x17a/0x200 > > [ 3323.071028] RSP: 0018:ffff8800c26edc78 EFLAGS: 00010246 > > [ 3323.071028] RAX: ffff88022febc000 RBX: ffff8800c26edde8 RCX: 0000000000000040 > > [ 3323.071028] RDX: 0000000000000000 RSI: ffff8800c2718cc0 RDI: 000000000203c000 > > [ 3323.071028] RBP: ffff8800c26edcb8 R08: 0000000000000000 R09: 0000000000000000 > > [ 3323.071028] R10: 0000000000000001 R11: 0000000000000001 R12: ffffea0008b9e240 > > [ 3323.071028] R13: ffffea00080f0000 R14: 00007fa2e6800000 R15: 00007fa2ffffffff > > [ 3323.071028] FS: 00007fa31e1b8700(0000) GS:ffff880230600000(0000) knlGS:0000000000000000 > > [ 3323.071028] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > > [ 3323.071028] CR2: 00007fa31e1e8990 CR3: 0000000005c25000 CR4: 00000000000006e0 > > [ 3323.071028] DR0: 0000000000698000 DR1: 0000000000698000 DR2: 0000000000698000 > > [ 3323.071028] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 > > [ 3323.071028] Stack: > > [ 3323.071028] 00000000000004de ffff88022e2139d0 ffff8800c26edcb8 ffff88021b7ef9a0 > > [ 3323.071028] 00007fa2e6800000 00007fa300000000 ffff8800c26edde8 00007fa2ffffffff > > [ 3323.071028] ffff8800c26edd48 ffffffff812800c6 ffffea0008454540 00007fa2e6a00000 > > [ 3323.071028] Call Trace: > > [ 3323.071028] [] unmap_page_range+0x2c6/0x410 > > [ 3323.071028] [] unmap_single_vma+0xf1/0x110 > > [ 3323.071028] [] unmap_vmas+0x61/0xa0 > > [ 3323.071028] [] exit_mmap+0xd0/0x170 > > [ 3323.071028] [] mmput+0x77/0xe0 > > [ 3323.071028] [] exit_mm+0x18d/0x1a0 > > [ 3323.071028] [] ? acct_collect+0x175/0x1b0 > > [ 3323.071028] [] do_exit+0x26a/0x510 > > [ 3323.071028] [] do_group_exit+0xa1/0xe0 > > [ 3323.071028] [] SyS_exit_group+0x12/0x20 > > [ 3323.071028] [] tracesys+0xdd/0xe2 > > [ 3323.071028] Code: 00 eb fe 66 0f 1f 44 00 00 48 8b 03 f0 48 81 80 60 03 00 00 00 fe ff ff 49 8b 45 00 f6 c4 40 75 18 31 f6 4c 89 ef e8 f6 1f f9 ff <0f> 0b 0f 1f 40 00 eb fe 66 0f 1f 44 00 00 48 8b 03 f0 48 ff 48 > > [ 3323.071028] RIP [] zap_huge_pmd+0x17a/0x200 > > [ 3323.071028] RSP > > This is still happening in -next. Anything else I can provide that'll be useful? I don't know... :( One theory I have is that the root cause of the bug is the same as with mm/huge_memory.c:1829 bug. If the compound page has been split but we miss the vma where PMD should be split, then we could see the effect. It could happend due anon_vma_interval_tree_foreach() vs. anon_vma_interval_tree_insert() race or something else. -- Kirill A. Shutemov