Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751572AbbBLRJ0 (ORCPT ); Thu, 12 Feb 2015 12:09:26 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:22311 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751505AbbBLRJX (ORCPT ); Thu, 12 Feb 2015 12:09:23 -0500 Message-ID: <54DCDDEE.5030501@oracle.com> Date: Thu, 12 Feb 2015 12:07:58 -0500 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins CC: Dave Hansen , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , Jerome Marchand , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv3 14/24] thp: implement new split_huge_page() References: <1423757918-197669-1-git-send-email-kirill.shutemov@linux.intel.com> <1423757918-197669-15-git-send-email-kirill.shutemov@linux.intel.com> In-Reply-To: <1423757918-197669-15-git-send-email-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5373 Lines: 102 On 02/12/2015 11:18 AM, Kirill A. Shutemov wrote: > +void __get_page_tail(struct page *page); > static inline void get_page(struct page *page) > { > - struct page *page_head = compound_head(page); > - VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page); > - atomic_inc(&page_head->_count); > + if (unlikely(PageTail(page))) > + return __get_page_tail(page); > + > + /* > + * Getting a normal page or the head of a compound page > + * requires to already have an elevated page->_count. > + */ > + VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page); This BUG_ON seems to get hit: [ 612.180784] page:ffffea00004cb180 count:0 mapcount:0 mapping: (null) index:0x2 [ 612.188538] flags: 0x1fffff80000000() [ 612.190452] page dumped because: VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0) [ 612.195857] ------------[ cut here ]------------ [ 612.196636] kernel BUG at include/linux/mm.h:463! [ 612.196636] invalid opcode: 0000 [#1] PREEMPT SMP KASAN [ 612.196636] Dumping ftrace buffer: [ 612.196636] (ftrace buffer empty) [ 612.196636] Modules linked in: [ 612.196636] CPU: 21 PID: 16300 Comm: trinity-c99 Not tainted 3.19.0-next-20150212-sasha-00072-gdc1aa32 #1913 [ 612.196636] task: ffff880012dbb000 ti: ffff880012df8000 task.ti: ffff880012df8000 [ 612.196636] RIP: copy_page_range (include/linux/mm.h:463 mm/memory.c:921 mm/memory.c:971 mm/memory.c:993 mm/memory.c:1055) [ 612.196636] RSP: 0018:ffff880012dffad0 EFLAGS: 00010286 [ 612.196636] RAX: dffffc0000000000 RBX: 00000000132c6100 RCX: 0000000000000000 [ 612.196636] RDX: 1ffffd4000099637 RSI: 0000000000000000 RDI: ffffea00004cb1b8 [ 612.196636] RBP: ffff880012dffc60 R08: 0000000000000001 R09: 0000000000000000 [ 612.196636] R10: ffffffffa5875ce8 R11: 0000000000000001 R12: ffff880012df6630 [ 612.196636] R13: ffff880711fe6630 R14: 00007f33954c6000 R15: 0000000000000010 [ 612.196636] FS: 00007f33993b0700(0000) GS:ffff880712800000(0000) knlGS:0000000000000000 [ 612.196636] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 612.196636] CR2: 00007f33993b06c8 CR3: 000000002ab33000 CR4: 00000000000007a0 [ 612.196636] DR0: ffffffff80000fff DR1: 0000000000000000 DR2: 0000000000000000 [ 612.196636] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000b1060a [ 612.196636] Stack: [ 612.196636] ffffffffa1937460 0000000000000002 ffff880012dffb30 ffffffff944141f6 [ 612.196636] ffff880012df8010 0000000000000020 ffff880012dffbf0 0000000000000000 [ 612.196636] 0000000008100073 1ffff100025bff7a ffff880012df1e50 1ffff100025bf002 [ 612.196636] Call Trace: [ 612.196636] ? __lock_is_held (kernel/locking/lockdep.c:3518) [ 612.196636] ? apply_to_page_range (mm/memory.c:1002) [ 612.196636] ? __vma_link_rb (mm/mmap.c:633) [ 612.196636] ? anon_vma_fork (mm/rmap.c:351) [ 612.196636] copy_process (kernel/fork.c:470 kernel/fork.c:869 kernel/fork.c:923 kernel/fork.c:1395) [ 612.196636] ? __cleanup_sighand (kernel/fork.c:1196) [ 612.196636] do_fork (kernel/fork.c:1659) [ 612.196636] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2554 kernel/locking/lockdep.c:2601) [ 612.196636] ? fork_idle (kernel/fork.c:1636) [ 612.196636] ? syscall_trace_enter_phase2 (arch/x86/kernel/ptrace.c:1598) [ 612.196636] SyS_clone (kernel/fork.c:1748) [ 612.196636] stub_clone (arch/x86/kernel/entry_64.S:517) [ 612.196636] ? tracesys_phase2 (arch/x86/kernel/entry_64.S:422) [ 612.196636] Code: ff df 48 89 f9 48 c1 e9 03 80 3c 11 00 0f 85 4c 04 00 00 48 8b 48 30 e9 fe f9 ff ff 48 c7 c6 40 34 f4 9e 48 89 c7 e8 0e ca fe ff <0f> 0b 0f 0b 48 89 c7 e8 12 2a ff ff e9 df fb ff ff 0f 0b 0f 0b All code ======== 0: ff df lcallq * 2: 48 89 f9 mov %rdi,%rcx 5: 48 c1 e9 03 shr $0x3,%rcx 9: 80 3c 11 00 cmpb $0x0,(%rcx,%rdx,1) d: 0f 85 4c 04 00 00 jne 0x45f 13: 48 8b 48 30 mov 0x30(%rax),%rcx 17: e9 fe f9 ff ff jmpq 0xfffffffffffffa1a 1c: 48 c7 c6 40 34 f4 9e mov $0xffffffff9ef43440,%rsi 23: 48 89 c7 mov %rax,%rdi 26: e8 0e ca fe ff callq 0xfffffffffffeca39 2b:* 0f 0b ud2 <-- trapping instruction 2d: 0f 0b ud2 2f: 48 89 c7 mov %rax,%rdi 32: e8 12 2a ff ff callq 0xffffffffffff2a49 37: e9 df fb ff ff jmpq 0xfffffffffffffc1b 3c: 0f 0b ud2 3e: 0f 0b ud2 ... Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: 0f 0b ud2 4: 48 89 c7 mov %rax,%rdi 7: e8 12 2a ff ff callq 0xffffffffffff2a1e c: e9 df fb ff ff jmpq 0xfffffffffffffbf0 11: 0f 0b ud2 13: 0f 0b ud2 ... [ 612.196636] RIP copy_page_range (include/linux/mm.h:463 mm/memory.c:921 mm/memory.c:971 mm/memory.c:993 mm/memory.c:1055) [ 612.196636] RSP Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/