From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id CA6EA6B0038 for ; Thu, 6 Oct 2016 17:01:07 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id r16so8577085pfg.4 for ; Thu, 06 Oct 2016 14:01:07 -0700 (PDT) Received: from mail1.windriver.com (mail1.windriver.com. [147.11.146.13]) by mx.google.com with ESMTPS id b6si4776707pfd.48.2016.10.06.14.01.06 for (version=TLS1_1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 06 Oct 2016 14:01:07 -0700 (PDT) Message-ID: <57F6BB8F.7070208@windriver.com> Date: Thu, 6 Oct 2016 15:01:03 -0600 From: Chris Friesen MIME-Version: 1.0 Subject: "swap_free: Bad swap file entry" and "BUG: Bad page map in process" but no swap configured Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: lkml , linux-mm@kvack.org I have Linux host running as a kvm hypervisor. It's running CentOS. (So the kernel is based on 3.10 but with loads of stuff backported by RedHat.) I realize this is not a mainline kernel, but I was wondering if anyone is aware of similar issues that had been fixed in mainline. When doing a bunch of live migrations eventually I hit a bunch of errors that look like this. 2016-10-03T23:13:54.017 controller-1 kernel: err [247517.457614] swap_free: Bad swap file entry 001fe858 2016-10-03T23:13:54.017 controller-1 kernel: alert [247517.463191] BUG: Bad page map in process qemu-kvm pte:3fd0b000 pmd:4557cb067 2016-10-03T23:13:54.017 controller-1 kernel: alert [247517.471352] addr:00007fefa9be4000 vm_flags:00100073 anon_vma:ffff88043f87ff80 mapping: (null) index:7fefa9be4 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483510] CPU: 0 PID: 154525 Comm: qemu-kvm Tainted: G OE ------------ 3.10.0-327.28.3.7.tis.x86_64 #1 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483513] Hardware name: Intel Corporation S2600WT2R/S2600WT2R, BIOS SE5C610.86B.01.01.0016.033120161139 03/31/2016 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483516] 00007fefa9be4000 0000000007795eb9 ffff88044007bc60 ffffffff81670503 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483524] ffff88044007bca8 ffffffff8115e70f 000000003fd0b000 00000007fefa9be4 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483531] ffff8804557cbf20 000000003fd0b000 00007fefa9c00000 00007fefa9be4000 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483538] Call Trace: 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483548] [] dump_stack+0x19/0x1b 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483553] [] print_bad_pte+0x1af/0x250 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483557] [] unmap_page_range+0x5a0/0x7f0 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483561] [] unmap_single_vma+0x59/0xd0 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483564] [] zap_page_range+0x105/0x170 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483568] [] SyS_madvise+0x3bc/0x7d0 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483573] [] ? SyS_futex+0x80/0x180 2016-10-03T23:13:54.017 controller-1 kernel: warning [247517.483577] [] system_call_fastpath+0x16/0x1b One interesting thing about the "Bad swap file entry" error is that these hosts do not have any swap configured: compute-4:~$ free total used free shared buff/cache available Mem: 131805464 122187644 8815864 245456 801956 9193644 Swap: 0 0 0 So why is the kernel calling swap_info_get()? In the second error, the offset in the SyS_madvise routine is here: 0xffffffff8115dd77 <+951>: callq 0xffffffff81161490 0xffffffff8115dd7c <+956>: xor %eax,%eax this maps to the second zap_page_range() call below in madvise_dontneed(): if (unlikely(vma->vm_flags & VM_NONLINEAR)) { struct zap_details details = { .nonlinear_vma = vma, .last_index = ULONG_MAX, }; zap_page_range(vma, start, end - start, &details); } else zap_page_range(vma, start, end - start, NULL); print_bad_pte() is called from this code in zap_pte_range(): if (pte_file(ptent)) { if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) print_bad_pte(vma, addr, ptent, NULL); Here's the interesting bit...we're calling print_bad_pte() here if "vma->vm_flags & VM_NONLINEAR" is not true...but we called zap_page_range() with a "details" of NULL specifically because it was not true. So probably pte_file(ptent) should not be true--but it is. Any of this sound familiar to anyone? Anyone have suggestions on how to bottom it out? Chris PS: Please CC me on replies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org