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Message-ID: <CANP1eJF9oyfTWL1up38cEFyQFZQU51v1Yo1wZqFYxN2qkvc7gQ@mail.gmail.com> Date: Sun, 8 Sep 2013 17:21:37 -0400 From: Milosz Tanski <milosz@...in.com> To: David Howells <dhowells@...hat.com> Cc: sprabhu@...hat.com, ceph-devel <ceph-devel@...r.kernel.org>, "Yan, Zheng" <zheng.z.yan@...el.com>, Hongyi Jia <jiayisuse@...il.com>, "linux-cachefs@...hat.com" <linux-cachefs@...hat.com>, "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, linux-kernel@...r.kernel.org, Sage Weil <sage@...tank.com> Subject: Re: [PATCH 0/8] ceph: fscache support & upstream changes David, I think that change does the trick. I had it running on the same machine for 5 hours and had the kernel forcefully drop some of the inodes in the cache (via drop caches) without a crash. I'll send a proper patch email after you take a look and make sure I did the right thing. Thanks, - Milosz On Sat, Sep 7, 2013 at 11:07 PM, Milosz Tanski <milosz@...in.com> wrote: > David, > > I ran into another issue that caused one my machines to hang on a > bunch of tasks and then hard lock. Here's the backtrace of the hang: > > INFO: task kworker/1:2:4214 blocked for more than 120 seconds. > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kworker/1:2 D ffff880443513fc0 0 4214 2 0x00000000 > Workqueue: ceph-msgr con_work [libceph] > ffff88042b093868 0000000000000246 ffff88042b8e5bc0 ffffffff81569fc6 > ffff88042c51dbc0 ffff88042b093fd8 ffff88042b093fd8 ffff88042b093fd8 > ffff88042c518000 ffff88042c51dbc0 ffff8804266b8d10 ffff8804439d7188 > Call Trace: > [<ffffffff81569fc6>] ? _raw_spin_unlock_irqrestore+0x16/0x20 > [<ffffffffa0016570>] ? fscache_wait_bit_interruptible+0x30/0x30 [fscache] > [<ffffffff81568d09>] schedule+0x29/0x70 > [<ffffffffa001657e>] fscache_wait_atomic_t+0xe/0x20 [fscache] > [<ffffffff815665cf>] out_of_line_wait_on_atomic_t+0x9f/0xe0 > [<ffffffff81083560>] ? autoremove_wake_function+0x40/0x40 > [<ffffffffa0015a9c>] __fscache_relinquish_cookie+0x15c/0x310 [fscache] > [<ffffffffa00a4fae>] ceph_fscache_unregister_inode_cookie+0x3e/0x50 [ceph] > [<ffffffffa007e373>] ceph_destroy_inode+0x33/0x200 [ceph] > [<ffffffff811c13ae>] ? __fsnotify_inode_delete+0xe/0x10 > [<ffffffff8119ba1c>] destroy_inode+0x3c/0x70 > [<ffffffff8119bb69>] evict+0x119/0x1b0 > [<ffffffff8119c3f3>] iput+0x103/0x190 > [<ffffffffa009aaed>] iterate_session_caps+0x7d/0x240 [ceph] > [<ffffffffa009b170>] ? remove_session_caps_cb+0x270/0x270 [ceph] > [<ffffffffa00a1fc5>] dispatch+0x725/0x1b40 [ceph] > [<ffffffff81459466>] ? kernel_recvmsg+0x46/0x60 > [<ffffffffa002c0e8>] ? ceph_tcp_recvmsg+0x48/0x60 [libceph] > [<ffffffffa002ecbe>] try_read+0xc1e/0x1e70 [libceph] > [<ffffffffa0030015>] con_work+0x105/0x1920 [libceph] > [<ffffffff8100349e>] ? xen_end_context_switch+0x1e/0x30 > [<ffffffff8108dbca>] ? finish_task_switch+0x5a/0xc0 > [<ffffffff8107aa59>] process_one_work+0x179/0x490 > [<ffffffff8107bf5b>] worker_thread+0x11b/0x370 > [<ffffffff8107be40>] ? manage_workers.isra.21+0x2e0/0x2e0 > [<ffffffff81082a80>] kthread+0xc0/0xd0 > [<ffffffff81010000>] ? perf_trace_xen_mmu_set_pud+0xd0/0xd0 > [<ffffffff810829c0>] ? flush_kthread_worker+0xb0/0xb0 > [<ffffffff81572cec>] ret_from_fork+0x7c/0xb0 > [<ffffffff810829c0>] ? flush_kthread_worker+0xb0/0xb0 > > It looks like it's waiting for the the cookie's n_active to drop down > to 0 ... but it isn't. After spending a bunch of hours reading the > code, then having a some beers (it is Saturday night after all), then > looking at code again... I think that the > __fscache_check_consistency() function increments the n_active counter > but never lowers it. I think the solution to this is the bellow diff > but I'm not a 100% sure. Can you let me know if I'm on the right > track... of it's beer googles? > > diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c > index 318e843..b2a86e3 100644 > --- a/fs/fscache/cookie.c > +++ b/fs/fscache/cookie.c > @@ -586,7 +586,8 @@ int __fscache_check_consistency(struct > fscache_cookie *cookie) > > fscache_operation_init(op, NULL, NULL); > op->flags = FSCACHE_OP_MYTHREAD | > - (1 << FSCACHE_OP_WAITING); > + (1 << FSCACHE_OP_WAITING) | > + (1 << FSCACHE_OP_UNUSE_COOKIE); > > spin_lock(&cookie->lock); > > Thanks, > - Milosz > > On Fri, Sep 6, 2013 at 4:03 PM, Sage Weil <sage@...tank.com> wrote: >> On Fri, 6 Sep 2013, Milosz Tanski wrote: >>> Sage, >>> >>> I've taken David's latest changes and per his request merged his >>> 'fscache-fixes-for-ceph' tag then applied my changes on top of that. >>> In addition to the pervious changes I also added a fix for the >>> warnings the linux-next build bot found. >>> >>> I've given the results a quick test to make sure it builds, boots and >>> runs okay. The code is located in my repository: >>> >>> https://adfin@...bucket.org/adfin/linux-fs.git in the wip-fscache-v2 branch >>> >>> I hope that this is the final go for now and thanks for everyone's patience. >> >> Looks good; I'll send this to Linus along with the other ceph patches >> shortly. >> >> Thanks, everyone! >> sage >> >> >>> >>> - Milosz >>> >>> On Fri, Sep 6, 2013 at 11:59 AM, David Howells <dhowells@...hat.com> wrote: >>> > Milosz Tanski <milosz@...in.com> wrote: >>> > >>> >> After running this for a day on some loaded machines I ran into what >>> >> looks like an old issue with the new code. I remember you saw an issue >>> >> that manifested it self in a similar way a while back. >>> >> >>> >> [13837253.462779] FS-Cache: Assertion failed >>> >> [13837253.462782] 3 == 5 is false >>> >> [13837253.462807] ------------[ cut here ]------------ >>> >> [13837253.462811] kernel BUG at fs/fscache/operation.c:414! >>> > >>> > Bah. >>> > >>> > I forgot to call fscache_op_complete(). Patch updated and repushed. >>> > >>> > Btw, I've reordered the patches to put the CIFS patch last. Can you merge the >>> > patches prior to the CIFS commit from my branch rather than cherry picking >>> > them so that if they go via two different routes, GIT will handle the merge >>> > correctly? I've stuck a tag on it (fscache-fixes-for-ceph) to make that >>> > easier for you. >>> > >>> > I've also asked another RH engineer to try doing some basic testing on the >>> > CIFS stuff - which may validate the fscache_readpages_cancel patch. >>> > >>> > David >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in >>> the body of a message to majordomo@...r.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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