From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966987AbaCUBcu (ORCPT ); Thu, 20 Mar 2014 21:32:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36392 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760110AbaCUADO (ORCPT ); Thu, 20 Mar 2014 20:03:14 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , Daniel Borkmann , Thomas Hellstrom , John David Anglin , HATAYAMA Daisuke , Konstantin Khlebnikov , Carsten Otte , Jared Hulbert , Hannes Frederic Sowa , "Kirill A. Shutemov" , Rik van Riel , Andrea Arcangeli , Andrew Morton , Linus Torvalds Subject: [PATCH 3.13 003/149] mm: include VM_MIXEDMAP flag in the VM_SPECIAL list to avoid m(un)locking Date: Thu, 20 Mar 2014 17:02:46 -0700 Message-Id: <20140321000436.820193965@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140321000436.377902063@linuxfoundation.org> References: <20140321000436.377902063@linuxfoundation.org> User-Agent: quilt/0.61-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vlastimil Babka commit 9050d7eba40b3d79551668f54e68fd6f51945ef3 upstream. Daniel Borkmann reported a VM_BUG_ON assertion failing: ------------[ cut here ]------------ kernel BUG at mm/mlock.c:528! invalid opcode: 0000 [#1] SMP Modules linked in: ccm arc4 iwldvm [...] video CPU: 3 PID: 2266 Comm: netsniff-ng Not tainted 3.14.0-rc2+ #8 Hardware name: LENOVO 2429BP3/2429BP3, BIOS G4ET37WW (1.12 ) 05/29/2012 task: ffff8801f87f9820 ti: ffff88002cb44000 task.ti: ffff88002cb44000 RIP: 0010:[] [] munlock_vma_pages_range+0x2e0/0x2f0 Call Trace: do_munmap+0x18f/0x3b0 vm_munmap+0x41/0x60 SyS_munmap+0x22/0x30 system_call_fastpath+0x1a/0x1f RIP munlock_vma_pages_range+0x2e0/0x2f0 ---[ end trace a0088dcf07ae10f2 ]--- because munlock_vma_pages_range() thinks it's unexpectedly in the middle of a THP page. This can be reproduced with default config since 3.11 kernels. A reproducer can be found in the kernel's selftest directory for networking by running ./psock_tpacket. The problem is that an order=2 compound page (allocated by alloc_one_pg_vec_page() is part of the munlocked VM_MIXEDMAP vma (mapped by packet_mmap()) and mistaken for a THP page and assumed to be order=9. The checks for THP in munlock came with commit ff6a6da60b89 ("mm: accelerate munlock() treatment of THP pages"), i.e. since 3.9, but did not trigger a bug. It just makes munlock_vma_pages_range() skip such compound pages until the next 512-pages-aligned page, when it encounters a head page. This is however not a problem for vma's where mlocking has no effect anyway, but it can distort the accounting. Since commit 7225522bb429 ("mm: munlock: batch non-THP page isolation and munlock+putback using pagevec") this can trigger a VM_BUG_ON in PageTransHuge() check. This patch fixes the issue by adding VM_MIXEDMAP flag to VM_SPECIAL, a list of flags that make vma's non-mlockable and non-mergeable. The reasoning is that VM_MIXEDMAP vma's are similar to VM_PFNMAP, which is already on the VM_SPECIAL list, and both are intended for non-LRU pages where mlocking makes no sense anyway. Related Lkml discussion can be found in [2]. [1] tools/testing/selftests/net/psock_tpacket [2] https://lkml.org/lkml/2014/1/10/427 Signed-off-by: Vlastimil Babka Signed-off-by: Daniel Borkmann Reported-by: Daniel Borkmann Tested-by: Daniel Borkmann Cc: Thomas Hellstrom Cc: John David Anglin Cc: HATAYAMA Daisuke Cc: Konstantin Khlebnikov Cc: Carsten Otte Cc: Jared Hulbert Tested-by: Hannes Frederic Sowa Cc: Kirill A. Shutemov Acked-by: Rik van Riel Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/mm.h | 2 +- mm/huge_memory.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -165,7 +165,7 @@ extern unsigned int kobjsize(const void * Special vmas that are non-mergable, non-mlock()able. * Note: mm/huge_memory.c VM_NO_THP depends on this definition. */ -#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP) +#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP) /* * mapping from the currently active vm_flags protection bits (the --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1960,7 +1960,7 @@ out: return ret; } -#define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE) +#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) int hugepage_madvise(struct vm_area_struct *vma, unsigned long *vm_flags, int advice)