Hi, On Mon, Nov 28, 2016 at 9:40 PM, Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote: > On Mon, 2016-11-28 at 11:10 +0800, Ming Lei wrote: >> Hi Guys, >> >> When I run stress-ng via the following steps on one ARM64 dual >> socket system(Cavium Thunder), the kernel oops[1] can often be >> triggered after running the stress test for several hours(sometimes >> it may take longer): >> >> - git clone git://kernel.ubuntu.com/cking/stress-ng.git >> - apply the attachment patch which just makes the posix file >> lock stress test more aggressive >> - run the test via '~/git/stress-ng$./stress-ng --lockf 128 --aggressive' >> >> >> From the oops log, looks one garbage file_lock node is got >> from the linked list of 'ctx->flc_posix' when the issue happens. >> >> BTW, the issue isn't observed on single socket Cavium Thunder yet, >> and the same issue can be seen on Ubuntu Xenial(v4.4 based kernel) >> too. >> >> Thanks, >> Ming >> > > Some questions just for clarification: > > - I assume this is being run on a local fs of some sort? ext4 or xfs or > something? > > - have you seen this on any other arch, besides ARM? > > The file locking code does do some lockless checking to see whether the > i_flctx is even present and whether the list is empty in > locks_remove_posix. It's possible we have some barrier problems there, I have used ebpf trace to see what is going on when 'stress-ng --lockf' is running, and almost all exported symbols in fs/locks.c are covered. Except for locks_alloc/locks_free/locks_copy/locks_init, the only observable symbols are fcntl_setlk, vfs_lock_file and locks_remove_posix, but locks_remove_posix() is just run at the begining and ending of the test. So seems not related with locks_remove_posix(). Then looks only fcntl_setlk() is running from different contexts during the test, but in this path, the 'ctx->flc_lock' is always held when operating the list. That said it is very strange to see the list corrupted even though it is protected by the lock. Thanks, Ming > but I don't quite see how that would cause us to have a corrupt lock on > the flc_posix list. > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
