Hello, The following program: // autogenerated by syzkaller (http://github.com/google/syzkaller) #include <syscall.h> #include <string.h> #include <stdint.h> #include <pthread.h> #define SYS_memfd_create 319 long fd; void *thr(void *p) { syscall(SYS_ftruncate, fd, 0x8ul, 0, 0, 0, 0); return 0; } int main() { pthread_t th; syscall(SYS_mmap, 0x20000000ul, 0x10000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul); memcpy((void*)0x20000f96, "\x23\x65\x6d\x31\x07\x2b\x27\x29\x00", 9); fd = syscall(SYS_memfd_create, 0x20000f96ul, 0x2ul, 0, 0, 0, 0); syscall(SYS_fallocate, fd, 0x0ul, 0x31d89288ul, 0x4ul, 0, 0); syscall(SYS_mmap, 0x20061000ul, 0xc00000ul, 0x1a9d91e04768640bul, 0x11ul, fd, 0x0ul); pthread_create(&th, 0, thr, 0); syscall(SYS_fstat, fd, 0x20550fcful, 0, 0, 0, 0); pthread_join(th, 0); return 0; } triggers WARNING in shmem_evict_inode: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 10442 at mm/shmem.c:625 shmem_evict_inode+0x335/0x480() Modules linked in: CPU: 1 PID: 8944 Comm: executor Not tainted 4.3.0+ #39 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 00000000ffffffff ffff88006c6afab8 ffffffff81aad406 0000000000000000 ffff88006e39ac80 ffffffff83091660 ffff88006c6afaf8 ffffffff81100829 ffffffff814192e5 ffffffff83091660 0000000000000271 ffff88003d075aa8 Call Trace: [<ffffffff81100a59>] warn_slowpath_null+0x29/0x30 kernel/panic.c:480 [<ffffffff814192e5>] shmem_evict_inode+0x335/0x480 mm/shmem.c:625 [<ffffffff8151560e>] evict+0x26e/0x580 fs/inode.c:542 [< inline >] iput_final fs/inode.c:1477 [<ffffffff81515f30>] iput+0x4a0/0x790 fs/inode.c:1504 [< inline >] dentry_iput fs/dcache.c:358 [<ffffffff8150667e>] __dentry_kill+0x4fe/0x700 fs/dcache.c:543 [< inline >] dentry_kill fs/dcache.c:587 [<ffffffff8150be7b>] dput+0x6ab/0x7a0 fs/dcache.c:796 [<ffffffff814c499b>] __fput+0x3fb/0x6e0 fs/file_table.c:226 [<ffffffff814c4d05>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff8115ab23>] task_work_run+0x163/0x1f0 kernel/task_work.c:115 [< inline >] exit_task_work include/linux/task_work.h:21 [<ffffffff81105049>] do_exit+0x7f9/0x2b80 kernel/exit.c:748 [<ffffffff8110b268>] do_group_exit+0x108/0x320 kernel/exit.c:878 [< inline >] SYSC_exit_group kernel/exit.c:889 [<ffffffff8110b49d>] SyS_exit_group+0x1d/0x20 kernel/exit.c:887 ---[ end trace 43da88a03e29c2a5 ]--- Run the program in a loop, as the WARNING seems to be triggered by a race. On commit d1e41ff11941784f469f17795a4d9425c2eb4b7a (Nov 5). But I was also able to reproduce it on a 3.11-based kernel. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>