On Sep 23, 2014, at 9:03 AM, Will Deacon <will.deacon@xxxxxxx> wrote: > Hi all, > > I've been running into the following warning on an arm64 system running > 3.17-rc6 with 64k pages. I've been unable to reproduce with a smaller page > size (4k). > > I don't yet have a concrete reproducer, but I've seen it hit a few times > today just running a machine with an NFS root filesystem and using ssh. > The warning seems to happen in parallel on the two CPUs, but I'm pretty > confident that our test_and_clear_bit implementation has the relevant > atomic instructions and memory barriers. > > Any ideas? > > Will So it looks like we’re either calling nfs_inode_remove_request twice on a request, or somehow not grabbing the inode reference for some request that is in the async write path. It’s interesting that these come in pairs - that has to mean something! Any more info on how to reproduce this would be really great. Unfortunately I don’t have access to an arm64 system. If it’s possible, could we get a packet trace around when this happens? This is pure speculation, but this might have something to do the resend path - a commit fails and all the requests on the commit list have to be resent. Have you noticed any side effects from this? That WARN_ON_ONCE was added to sanity test the new page group code and we need to fix this, but I’m wondering if anything “bad” happens… -dros > > --->8 > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 1023 at fs/nfs/write.c:743 nfs_inode_remove_request+0xe4/0xf0() > Modules linked in: > CPU: 1 PID: 1023 Comm: kworker/1:2 Not tainted 3.17.0-rc6 #1 > Workqueue: nfsiod rpc_async_release > Call trace: > [<fffffe0000096410>] dump_backtrace+0x0/0x130 > [<fffffe0000096550>] show_stack+0x10/0x1c > [<fffffe00004cda94>] dump_stack+0x74/0xbc > [<fffffe00000b4d20>] warn_slowpath_common+0x8c/0xb4 > [<fffffe00000b4e0c>] warn_slowpath_null+0x14/0x20 > [<fffffe000027a6a8>] nfs_inode_remove_request+0xe0/0xf0 > [<fffffe000027b704>] nfs_write_completion+0xb4/0x150 > [<fffffe0000276ef4>] nfs_pgio_release+0x34/0x44 > [<fffffe00004ac2d0>] rpc_free_task+0x24/0x4c > [<fffffe00004ac5c0>] rpc_async_release+0xc/0x18 > [<fffffe00000c89e8>] process_one_work+0x140/0x32c > [<fffffe00000c9338>] worker_thread+0x13c/0x470 > [<fffffe00000cd9e4>] kthread+0xd0/0xe8 > ---[ end trace 6f044efb83f0811b ]--- > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 621 at fs/nfs/write.c:743 nfs_inode_remove_request+0xe4/0xf0() > CPU: 0 PID: 621 Comm: kworker/0:2 Tainted: G W 3.17.0-rc6 #1 > Workqueue: nfsiod rpc_async_release > Call trace: > [<fffffe0000096410>] dump_backtrace+0x0/0x130 > [<fffffe0000096550>] show_stack+0x10/0x1c > [<fffffe00004cda94>] dump_stack+0x74/0xbc > [<fffffe00000b4d20>] warn_slowpath_common+0x8c/0xb4 > [<fffffe00000b4e0c>] warn_slowpath_null+0x14/0x20 > [<fffffe000027a6a8>] nfs_inode_remove_request+0xe0/0xf0 > [<fffffe000027b704>] nfs_write_completion+0xb4/0x150 > [<fffffe0000276ef4>] nfs_pgio_release+0x34/0x44 > [<fffffe00004ac2d0>] rpc_free_task+0x24/0x4c > [<fffffe00004ac5c0>] rpc_async_release+0xc/0x18 > [<fffffe00000c89e8>] process_one_work+0x140/0x32c > [<fffffe00000c9338>] worker_thread+0x13c/0x470 > [<fffffe00000cd9e4>] kthread+0xd0/0xe8 > ---[ end trace 6f044efb83f0811c ]--- -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
