From: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Subject: mm/hugetlb.c: don't call region_abort if region_chg fails 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 (when using an injected kmalloc failure) 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 Link: http://lkml.kernel.org/r/1490821682-23228-1-git-send-email-mike.kravetz@xxxxxxxxxx Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/hugetlb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN mm/hugetlb.c~mm-hugetlb-dont-call-region_abort-if-region_chg-fails mm/hugetlb.c --- a/mm/hugetlb.c~mm-hugetlb-dont-call-region_abort-if-region_chg-fails +++ a/mm/hugetlb.c @@ -4403,7 +4403,9 @@ int hugetlb_reserve_pages(struct 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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
