syzbot has found a reproducer for the following issue on: HEAD commit: 4fa56ad0 Merge tag 'for-linus' of git://git.kernel.org/pub.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12390a96d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=b8dbd3c72fdc7777 dashboard link: https://syzkaller.appspot.com/bug?extid=d9e482e303930fa4f6ff syz repro: https://syzkaller.appspot.com/x/repro.syz?x=109aaa7ed00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16e77d16d00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+d9e482e303930fa4f6ff@xxxxxxxxxxxxxxxxxxxxxxxxx executing program BUG: memory leak unreferenced object 0xffff888111edd780 (size 32): comm "syz-executor633", pid 8448, jiffies 4294951405 (age 17.620s) hex dump (first 32 bytes): 10 64 d1 0f 81 88 ff ff 00 10 7e 12 81 88 ff ff .d........~..... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff81744606>] kmalloc include/linux/slab.h:554 [inline] [<ffffffff81744606>] ext4_multi_mount_protect+0x4a6/0x5d0 fs/ext4/mmp.c:367 [<ffffffff81783614>] ext4_fill_super+0x56a4/0x5b20 fs/ext4/super.c:4769 [<ffffffff8154ebf3>] mount_bdev+0x223/0x260 fs/super.c:1367 [<ffffffff815aee7b>] legacy_get_tree+0x2b/0x90 fs/fs_context.c:592 [<ffffffff8154c7e8>] vfs_get_tree+0x28/0x100 fs/super.c:1497 [<ffffffff8158c8ee>] do_new_mount fs/namespace.c:2903 [inline] [<ffffffff8158c8ee>] path_mount+0xc3e/0x1120 fs/namespace.c:3233 [<ffffffff8158d51e>] do_mount fs/namespace.c:3246 [inline] [<ffffffff8158d51e>] __do_sys_mount fs/namespace.c:3454 [inline] [<ffffffff8158d51e>] __se_sys_mount fs/namespace.c:3431 [inline] [<ffffffff8158d51e>] __x64_sys_mount+0x18e/0x1d0 fs/namespace.c:3431 [<ffffffff842ded2d>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 [<ffffffff84400068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
