Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933103AbdC2VJU (ORCPT ); Wed, 29 Mar 2017 17:09:20 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:33961 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932707AbdC2VIT (ORCPT ); Wed, 29 Mar 2017 17:08:19 -0400 From: Mike Kravetz To: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Hillf Danton , Michal Hocko , "Kirill A . Shutemov" , Andrey Ryabinin , Naoya Horiguchi , Mike Kravetz Subject: [PATCH RESEND] mm/hugetlb: Don't call region_abort if region_chg fails Date: Wed, 29 Mar 2017 14:08:02 -0700 Message-Id: <1490821682-23228-1-git-send-email-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.7.4 X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1960 Lines: 53 Resending because of typo in Andrew's e-mail when first sent Changes to hugetlbfs reservation maps is a two step process. The first step is a call to region_chg to determine what needs to be changed, and prepare that change. This should be followed by a call to call to region_add to commit the change, or region_abort to abort the change. The error path in hugetlb_reserve_pages called region_abort after a failed call to region_chg. As a result, the adds_in_progress counter in the reservation map is off by 1. This is caught by a VM_BUG_ON in resv_map_release when the reservation map is freed. syzkaller fuzzer found this bug, that resulted in the following: kernel BUG at mm/hugetlb.c:742! Call Trace: hugetlbfs_evict_inode+0x7b/0xa0 fs/hugetlbfs/inode.c:493 evict+0x481/0x920 fs/inode.c:553 iput_final fs/inode.c:1515 [inline] iput+0x62b/0xa20 fs/inode.c:1542 hugetlb_file_setup+0x593/0x9f0 fs/hugetlbfs/inode.c:1306 newseg+0x422/0xd30 ipc/shm.c:575 ipcget_new ipc/util.c:285 [inline] ipcget+0x21e/0x580 ipc/util.c:639 SYSC_shmget ipc/shm.c:673 [inline] SyS_shmget+0x158/0x230 ipc/shm.c:657 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: resv_map_release+0x265/0x330 mm/hugetlb.c:742 Reported-by: Dmitry Vyukov Signed-off-by: Mike Kravetz Acked-by: Hillf Danton --- mm/hugetlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index c7025c1..c65d45c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4233,7 +4233,9 @@ int hugetlb_reserve_pages(struct inode *inode, return 0; out_err: if (!vma || vma->vm_flags & VM_MAYSHARE) - region_abort(resv_map, from, to); + /* Don't call region_abort if region_chg failed */ + if (chg >= 0) + region_abort(resv_map, from, to); if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) kref_put(&resv_map->refs, resv_map_release); return ret; -- 2.7.4