On Wed, Jul 09, 2014 at 04:37:44PM -0400, Jeff Layton wrote: > On Wed, 9 Jul 2014 15:41:14 -0400 > "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > > > On Wed, Jul 09, 2014 at 01:21:21AM -0700, Christoph Hellwig wrote: > > > On Tue, Jul 08, 2014 at 05:11:34PM -0400, J. Bruce Fields wrote: > > > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 > > > > IP: [<ffffffff810890b1>] process_one_work+0x31/0x500 > > > > PGD 0 > > > > Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > > > > Modules linked in: nfsd auth_rpcgss oid_registry nfs_acl lockd sunrpc > > > > CPU: 2 PID: 30 Comm: kworker/u8:1 Not tainted 3.16.0-rc2-00023-g30c1d16 #3051 > > > > Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > > > > task: ffff88003d9cc810 ti: ffff88003d9d0000 task.ti: ffff88003d9d0000 > > > > RIP: 0010:[<ffffffff810890b1>] [<ffffffff810890b1>] process_one_work+0x31/0x500 > > > > RSP: 0018:ffff88003d9d3d68 EFLAGS: 00010046 > > > > RAX: 0000000000000100 RBX: ffff88003d9caf80 RCX: dead000000200200 > > > > RDX: 0000000000000100 RSI: ffff880031429b38 RDI: ffff88003d9caf80 > > > > RBP: ffff88003d9d3dd8 R08: ffff88003dcb7800 R09: 0000000001c40000 > > > > R10: 0000000000000000 R11: 000000000006b5b0 R12: ffff88003dcb7800 > > > > R13: 0000000000000000 R14: ffff880031429b38 R15: ffff88003d9caf80 > > > > FS: 0000000000000000(0000) GS:ffff88003fb00000(0000) knlGS:0000000000000000 > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > > > > CR2: 0000000000000138 CR3: 0000000027744000 CR4: 00000000000006e0 > > > > Stack: > > > > 000000003d9d3d88 ffff88003dcb7818 ffff88003d9cafb0 ffff88003dcb7800 > > > > ffff88003dcb7800 ffff88003dcb7800 ffff88003dcb7800 ffff88003d9cafb0 > > > > ffff88003d9d3dd8 ffff88003dcb7800 ffff88003dcb7848 ffff88003d9cafb0 > > > > Call Trace: > > > > [<ffffffff81089b9b>] worker_thread+0x11b/0x4f0 > > > > [<ffffffff81089a80>] ? init_pwq+0x190/0x190 > > > > [<ffffffff81090ac4>] kthread+0xe4/0x100 > > > > [<ffffffff810909e0>] ? __init_kthread_worker+0x70/0x70 > > > > [<ffffffff81a4ca2c>] ret_from_fork+0x7c/0xb0 > > > > [<ffffffff810909e0>] ? __init_kthread_worker+0x70/0x70 > > > > Code: 48 89 e5 41 57 41 56 49 89 f6 41 55 45 31 ed 41 54 53 48 89 fb 48 83 ec 48 48 8b 06 4c 8b 67 48 48 89 c2 30 d2 a8 04 4c 0f 45 ea <49> 8b 45 08 48 c7 45 b8 00 00 00 00 48 c7 45 c0 00 00 00 00 8b > > > > RIP [<ffffffff810890b1>] process_one_work+0x31/0x500 > > > > RSP <ffff88003d9d3d68> > > > > CR2: 0000000000000008 > > > > > > > > and I'm suspicious of this: > > > > > > > > > @@ -763,6 +764,8 @@ static void do_probe_callback(struct nfs4_client *clp) > > > > > > > > > > cb->cb_ops = &nfsd4_cb_probe_ops; > > > > > > > > > > + INIT_WORK(&cb->cb_work, nfsd4_do_callback_rpc); > > > > > + > > > > > run_nfsd4_cb(cb); > > > > > } > > > > > > > > This is called all over the place, possibly multiple times on the same > > > > client, so we're calling INIT_WORK on something that may already be in > > > > use--I doubt that's safe. > > > > > > > > I'm backing out this patch for now. > > > > > > If that's the case all of do_probe_callback seems very fishy to me, as > > > it scrambles all over the callback structure. I guess we need to move > > > more of it to an init function then, and have different init functions > > > for the different callbacks. > > > > Taking a look.... It does look fishy, but those fields are constant, so > > I don't see a bug. > > > > In delegation recall case (nfsd4_cb_recall()) those fields aren't > > constant, but we guarantee it's only called once. > > > > Yes. I'm inclined to leave well enough alone on this and to leave any > cleanup in this area to Christoph since he said he was overhauling that > code anyway. > > I didn't see where you had reverted the patch in your repo, Yeah, reverted locally but I had a testing problem that's kept me from pushing it out yet. > so I went > ahead and did it and then rebased the series on top of the revert. > There were some merge conflicts, but I at least was able to get rid of > the double INIT_WORK calls in the case of a delegation (and do some > related cleanup in this area): > > http://git.samba.org/?p=jlayton/linux.git;a=commitdiff;h=60b61375d6a84e74bf1c3c7c230712721e14773d > http://git.samba.org/?p=jlayton/linux.git;a=commitdiff;h=491192c3e6f0966722c34ba36adfde7575640544 > > Unfortunately there are a few (fairly trivial) merge conflicts later in > the series due to this change. Bruce, do you want me to repost the > whole set, or would you rather just cherry-pick them from my updated > branch? Let's spare everyone a reposting and I'll see how far I can get with fixing up the conflicts myself and/or cherry-picking from your updated branch. --b. -- 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
