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Wed, 6 Jul 2016 18:18:22 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Wed, 6 Jul 2016 18:18:22 +0300 From: Konstantin Belousov To: David Cross Cc: freebsd-stable@freebsd.org, freebsd-hackers@freebsd.org Subject: Re: Reproducable panic in FFS with softupdates and no journaling (10.3-RELEASE-pLATEST) Message-ID: <20160706151822.GC38613@kib.kiev.ua> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.1 (2016-04-27) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Jul 2016 15:18:36 -0000 On Wed, Jul 06, 2016 at 10:51:28AM -0400, David Cross wrote: > Ok.. to reply to my own message, I using ktr and debugging printfs I have > found the culprit.. but I am still at a loss to 'why', or what the > appropriate fix is. > > Lets go back to the panic (simplified) > > #0 0xffffffff8043f160 at kdb_backtrace+0x60 > #1 0xffffffff80401454 at vpanic+0x124 > #2 0xffffffff804014e3 at panic+0x43 > #3 0xffffffff8060719a at softdep_deallocate_dependencies+0x6a > #4 0xffffffff80499cc1 at brelse+0x151 > #5 0xffffffff804979b1 at bufwrite+0x81 > #6 0xffffffff80623c80 at ffs_write+0x4b0 > #7 0xffffffff806ce9a4 at VOP_WRITE_APV+0x1c4 > #8 0xffffffff806639e3 at vnode_pager_generic_putpages+0x293 > #9 0xffffffff806d2102 at VOP_PUTPAGES_APV+0x142 > #10 0xffffffff80661cc1 at vnode_pager_putpages+0x91 > #11 0xffffffff806588e6 at vm_pageout_flush+0x116 > #12 0xffffffff806517e2 at vm_object_page_collect_flush+0x1c2 > #13 0xffffffff80651519 at vm_object_page_clean+0x179 > #14 0xffffffff80651102 at vm_object_terminate+0xa2 > #15 0xffffffff806621a5 at vnode_destroy_vobject+0x85 > #16 0xffffffff8062a52f at ufs_reclaim+0x1f > #17 0xffffffff806d0782 at VOP_RECLAIM_APV+0x142 > > Via KTR logging I determined that the dangling dependedency was on a > freshly allocated buf, *after* vinvalbuf in the vgonel() (so in VOP_RECLAIM > itself), called by the vnode lru cleanup process; I further noticed that it > was in a newbuf that recycled a bp (unimportant, except it let me narrow > down my logging to something managable), from there I get this stacktrace > (simplified) > > #0 0xffffffff8043f160 at kdb_backtrace+0x60 > #1 0xffffffff8049c98e at getnewbuf+0x4be > #2 0xffffffff804996a0 at getblk+0x830 > #3 0xffffffff805fb207 at ffs_balloc_ufs2+0x1327 > #4 0xffffffff80623b0b at ffs_write+0x33b > #5 0xffffffff806ce9a4 at VOP_WRITE_APV+0x1c4 > #6 0xffffffff806639e3 at vnode_pager_generic_putpages+0x293 > #7 0xffffffff806d2102 at VOP_PUTPAGES_APV+0x142 > #8 0xffffffff80661cc1 at vnode_pager_putpages+0x91 > #9 0xffffffff806588e6 at vm_pageout_flush+0x116 > #10 0xffffffff806517e2 at vm_object_page_collect_flush+0x1c2 > #11 0xffffffff80651519 at vm_object_page_clean+0x179 > #12 0xffffffff80651102 at vm_object_terminate+0xa2 > #13 0xffffffff806621a5 at vnode_destroy_vobject+0x85 > #14 0xffffffff8062a52f at ufs_reclaim+0x1f > #15 0xffffffff806d0782 at VOP_RECLAIM_APV+0x142 > #16 0xffffffff804b6c6e at vgonel+0x2ee > #17 0xffffffff804ba6f5 at vnlru_proc+0x4b5 > > addr2line on the ffs_balloc_ufs2 gives: > /usr/src/sys/ufs/ffs/ffs_balloc.c:778: > > bp = getblk(vp, lbn, nsize, 0, 0, gbflags); > bp->b_blkno = fsbtodb(fs, newb); > if (flags & BA_CLRBUF) > vfs_bio_clrbuf(bp); > if (DOINGSOFTDEP(vp)) > softdep_setup_allocdirect(ip, lbn, newb, 0, > nsize, 0, bp); > > > Boom, freshly allocated buffer with a dependecy; nothing in VOP_RECLAIM > handles this, this is after vinvalbuf is called, it expects that everything > is flushed to disk and its just about releasing structures (is my read of > the code). > > Now, perhaps this is a good assumption? the question then is how is this > buffer hanging out there surviving a a vinvalbuf. I will note that my > test-case that finds this runs and terminates *minutes* before... its not > just hanging out there in a race, its surviving background sync, fsync, > etc... wtf? Also, I *can* unmount the FS without an error, so that > codepath is either ignoring this buffer, or its forcing a sync in a way > that doesn't panic? Most typical cause for the buffer dependencies not flushed is a buffer write error. At least you could provide the printout of the buffer to confirm or reject this assumption. Were there any kernel messages right before the panic ? Just in case, did you fsck the volume before using it, after the previous panic ? > > Anyone have next steps? I am making progress here, but its really slow > going, this is probably the most complex portion of the kernel and some > pointers would be helpful. > > On Sat, Jul 2, 2016 at 2:31 PM, David Cross wrote: > > > Ok, I have been trying to trace this down for awhile..I know quite a bit > > about it.. but there's a lot I don't know, or I would have a patch. I have > > been trying to solve this on my own, but bringing in some outside > > assistance will let me move on with my life. > > > > First up: The stacktrace (from a debugging kernel, with coredump > > > > #0 doadump (textdump=1) at /usr/src/sys/kern/kern_shutdown.c:298 > > #1 0xffffffff8071018a in kern_reboot (howto=260) > > at /usr/src/sys/kern/kern_shutdown.c:486 > > #2 0xffffffff80710afc in vpanic ( > > fmt=0xffffffff80c7a325 "softdep_deallocate_dependencies: dangling deps > > b_ioflags: %d, b_bufsize: %ld, b_flags: %d, bo_flag: %d", > > ap=0xfffffe023ae5cf40) > > at /usr/src/sys/kern/kern_shutdown.c:889 > > #3 0xffffffff807108c0 in panic ( > > fmt=0xffffffff80c7a325 "softdep_deallocate_dependencies: dangling deps > > b_ioflags: %d, b_bufsize: %ld, b_flags: %d, bo_flag: %d") > > at /usr/src/sys/kern/kern_shutdown.c:818 > > #4 0xffffffff80a7c841 in softdep_deallocate_dependencies ( > > bp=0xfffffe01f030e148) at /usr/src/sys/ufs/ffs/ffs_softdep.c:14099 > > #5 0xffffffff807f793f in buf_deallocate (bp=0xfffffe01f030e148) at > > buf.h:428 > > #6 0xffffffff807f59c9 in brelse (bp=0xfffffe01f030e148) > > at /usr/src/sys/kern/vfs_bio.c:1599 > > #7 0xffffffff807f3132 in bufwrite (bp=0xfffffe01f030e148) > > at /usr/src/sys/kern/vfs_bio.c:1180 > > #8 0xffffffff80ab226a in bwrite (bp=0xfffffe01f030e148) at buf.h:395 > > #9 0xffffffff80aafb1b in ffs_write (ap=0xfffffe023ae5d2b8) > > at /usr/src/sys/ufs/ffs/ffs_vnops.c:800 > > #10 0xffffffff80bdf0ed in VOP_WRITE_APV (vop=0xffffffff80f15480, > > a=0xfffffe023ae5d2b8) at vnode_if.c:999 > > #11 0xffffffff80b1d02e in VOP_WRITE (vp=0xfffff80077e7a000, > > uio=0xfffffe023ae5d378, ioflag=8323232, cred=0xfffff80004235000) > > at vnode_if.h:413 > > #12 0xffffffff80b1ce97 in vnode_pager_generic_putpages > > (vp=0xfffff80077e7a000, > > ma=0xfffffe023ae5d660, bytecount=16384, flags=1, > > rtvals=0xfffffe023ae5d580) > > at /usr/src/sys/vm/vnode_pager.c:1138 > > #13 0xffffffff80805a57 in vop_stdputpages (ap=0xfffffe023ae5d478) > > at /usr/src/sys/kern/vfs_default.c:760 > > #14 0xffffffff80be201e in VOP_PUTPAGES_APV (vop=0xffffffff80f00218, > > a=0xfffffe023ae5d478) at vnode_if.c:2861 > > #15 0xffffffff80b1d7e3 in VOP_PUTPAGES (vp=0xfffff80077e7a000, > > m=0xfffffe023ae5d660, count=16384, sync=1, rtvals=0xfffffe023ae5d580, > > offset=0) at vnode_if.h:1189 > > #16 0xffffffff80b196f3 in vnode_pager_putpages (object=0xfffff8014a1fce00, > > m=0xfffffe023ae5d660, count=4, flags=1, rtvals=0xfffffe023ae5d580) > > at /usr/src/sys/vm/vnode_pager.c:1016 > > #17 0xffffffff80b0a605 in vm_pager_put_pages (object=0xfffff8014a1fce00, > > m=0xfffffe023ae5d660, count=4, flags=1, rtvals=0xfffffe023ae5d580) > > at vm_pager.h:144 > > #18 0xffffffff80b0a18c in vm_pageout_flush (mc=0xfffffe023ae5d660, > > count=4, > > flags=1, mreq=0, prunlen=0xfffffe023ae5d6f8, eio=0xfffffe023ae5d77c) > > at /usr/src/sys/vm/vm_pageout.c:533 > > #19 0xffffffff80afec76 in vm_object_page_collect_flush ( > > object=0xfffff8014a1fce00, p=0xfffff8023a882370, pagerflags=1, > > flags=1, > > clearobjflags=0xfffffe023ae5d780, eio=0xfffffe023ae5d77c) > > at /usr/src/sys/vm/vm_object.c:971 > > #20 0xffffffff80afe91e in vm_object_page_clean (object=0xfffff8014a1fce00, > > start=0, end=0, flags=1) at /usr/src/sys/vm/vm_object.c:897 > > #21 0xffffffff80afe1fa in vm_object_terminate (object=0xfffff8014a1fce00) > > at /usr/src/sys/vm/vm_object.c:735 > > #22 0xffffffff80b1a0f1 in vnode_destroy_vobject (vp=0xfffff80077e7a000) > > at /usr/src/sys/vm/vnode_pager.c:164 > > #23 0xffffffff80abb191 in ufs_prepare_reclaim (vp=0xfffff80077e7a000) > > at /usr/src/sys/ufs/ufs/ufs_inode.c:190 > > #24 0xffffffff80abb1f9 in ufs_reclaim (ap=0xfffffe023ae5d968) > > at /usr/src/sys/ufs/ufs/ufs_inode.c:219 > > #25 0xffffffff80be0ade in VOP_RECLAIM_APV (vop=0xffffffff80f15ec0, > > a=0xfffffe023ae5d968) at vnode_if.c:2019 > > #26 0xffffffff80827849 in VOP_RECLAIM (vp=0xfffff80077e7a000, > > td=0xfffff80008931960) at vnode_if.h:830 > > #27 0xffffffff808219a9 in vgonel (vp=0xfffff80077e7a000) > > at /usr/src/sys/kern/vfs_subr.c:2943 > > #28 0xffffffff808294e8 in vlrureclaim (mp=0xfffff80008b2e000) > > at /usr/src/sys/kern/vfs_subr.c:882 > > #29 0xffffffff80828ea9 in vnlru_proc () at > > /usr/src/sys/kern/vfs_subr.c:1000 > > #30 0xffffffff806b66c5 in fork_exit (callout=0xffffffff80828c50 > > , > > arg=0x0, frame=0xfffffe023ae5dc00) at > > /usr/src/sys/kern/kern_fork.c:1027 > > #31 0xffffffff80b21dce in fork_trampoline () > > at /usr/src/sys/amd64/amd64/exception.S:611 > > #32 0x0000000000000000 in ?? () > > > > This is a kernel compiled -O -g, its "almost" GENERIC; the only difference > > is some removed drivers, I have reproduced this on a few different kernels, > > including a BHYVE one so I can poke at it and not take out the main > > machine. The reproduction as it currently stands needs to have jails > > running, but I don't believe this is a jail interaction, I think its just > > that the process that sets up the problem happens to be running in a jail. > > The step is "start jail; run "find /mountpoint -xdev >/dev/null" on the > > filesystem, when the vnlru forces the problem vnode out the system panics. > > > > I made a few modifications to the kernel to spit out information about the > > buf that causes the issue, but that is it. > > > > Information about the buf in question; it has a single softdependency > > worklist for direct allocation: > > (kgdb) print *bp->b_dep->lh_first > > $6 = {wk_list = {le_next = 0x0, le_prev = 0xfffffe01f030e378}, > > wk_mp = 0xfffff80008b2e000, wk_type = 4, wk_state = 163841} > > > > The file that maps to that buffer: > > ls -lh MOUNTPOINT/jails/mail/var/imap/db/__db.002 > > -rw------- 1 cyrus cyrus 24K Jul 1 20:32 > > MOUNTPOINT/jails/mail/var/imap/db/__db.002 > > > > Any help is appreciated, until then I will keep banging my head against > > the proverbial wall on this :) > > > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"