Date: Mon, 28 Mar 2016 08:58:29 -0700 From: Maxim Sobolev <sobomax@FreeBSD.org> To: stable@freebsd.org, freebsd-fs@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org> Cc: Kirk McKusick <mckusick@mckusick.com>, kib@freebsd.org Subject: Re: Process stuck in "vnread" Message-ID: <CAH7qZfuURZ5SowJ7iHWZyfpeb1ehpCdLGQTnQKLWtwh6um-=KA@mail.gmail.com> In-Reply-To: <CAH7qZftHP0b30AnF4Fds9%2BotY0Y24HMFuO=RmkqcBJD3wFNkHg@mail.gmail.com> References: <CAH7qZfs3EwT8jnKyodHxF_5nK18MeLSaB_F-qqOfwV0MJMD7Vg@mail.gmail.com> <CAH7qZfssCPxc_uuMoxwAqa6qdi1y=VCqRT6hk-=mTU15RwOCAg@mail.gmail.com> <CAH7qZftHP0b30AnF4Fds9%2BotY0Y24HMFuO=RmkqcBJD3wFNkHg@mail.gmail.com>
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P.S. That being said, I am not sure if that write operation on md(4) happen before or after the offending lockup in the zfs_freebsd_write(), so it might be just as well be the result of that, not cause. On Mon, Mar 28, 2016 at 8:52 AM, Maxim Sobolev <sobomax@sippysoft.com> wrote: > Done some head scratching, it looks like it's got page fault in the > copyin() (cp(1) AFAIK mmaps source file). There might be some interlock > issue between competing write to the same ZFS, the md0 device is locked > forever waiting for the write operation to complete at the very same time. > I am curious as to whether we are allowed to sleep in the dmu_write_uio_dbuf(), > AFAIK dmu is ZFS's transaction layer, so maybe copyin() should be done > earlier to avoid possible page fault in there? > > (kgdb) thread 465 > [Switching to thread 465 (Thread 100530)]#0 sched_switch > (td=0xfffff8037b8ff960, newtd=<value optimized out>, flags=<value optimized > out>) at /usr/home/sobomax/projects/freebsd103/sys/kern/sched_ule.c:1945 > 1945 cpuid = PCPU_GET(cpuid); > (kgdb) bt > #0 sched_switch (td=0xfffff8037b8ff960, newtd=<value optimized out>, > flags=<value optimized out>) at > /usr/home/sobomax/projects/freebsd103/sys/kern/sched_ule.c:1945 > #1 0xffffffff809364d1 in mi_switch (flags=260, newtd=0x0) at > /usr/home/sobomax/projects/freebsd103/sys/kern/kern_synch.c:491 > #2 0xffffffff809761ca in sleepq_wait (wchan=0x0, pri=0) at > /usr/home/sobomax/projects/freebsd103/sys/kern/subr_sleepqueue.c:618 > #3 0xffffffff808d843d in _cv_wait (cvp=0xfffff8001041b220, > lock=0xfffff8001041b1b8) at > /usr/home/sobomax/projects/freebsd103/sys/kern/kern_condvar.c:151 > #4 0xffffffff81a431e5 in txg_wait_synced () from /boot/kernel/zfs.ko > #5 0xffffffff81a62fa9 in zil_commit () from /boot/kernel/zfs.ko > #6 0xffffffff81a9216b in zfs_freebsd_write () from /boot/kernel/zfs.ko > #7 0xffffffff80dd6219 in VOP_WRITE_APV (vop=<value optimized out>, > a=<value optimized out>) at vnode_if.c:999 > #8 0xffffffff8060b69a in mdstart_vnode (sc=0xfffff80057f78000, > bp=0xfffff8036d4660f8) at vnode_if.h:413 > #9 0xffffffff8060caad in md_kthread (arg=0xfffff80057f78000) at > /usr/home/sobomax/projects/freebsd103/sys/dev/md/md.c:1147 > #10 0xffffffff808f6e6a in fork_exit (callout=0xffffffff8060c900 > <md_kthread>, arg=0xfffff80057f78000, frame=0xfffffe04689b2ac0) at > /usr/home/sobomax/projects/freebsd103/sys/kern/kern_fork.c:1027 > #11 0xffffffff80ca0a5e in fork_trampoline () at > /usr/home/sobomax/projects/freebsd103/sys/amd64/amd64/exception.S:611 > #12 0x0000000000000000 in ?? () > > > On Mon, Mar 28, 2016 at 7:31 AM, Maxim Sobolev <sobomax@sippysoft.com> > wrote: > >> OK, that happened again. Now it's 10.3-RC3, funny enough, it's the same >> "cp" command. Any ideas about what can be wrong here? The box is still up, >> so if you need me to do something specific inside kgdb please let me know. >> Thanks! >> >> $ uname -a >> FreeBSD abc01.sippysoft.com 10.3-RC3 FreeBSD 10.3-RC3 #0 >> bedc749(master): Wed Mar 23 14:39:07 PDT 2016 >> sobomax@abc01.sippysoft.com:/usr/obj/usr/home/sobomax/projects/freebsd103/sys/ABC01 >> amd64 >> >> >> $ ps -xaHl -O lwp >> UID PID PPID CPU PRI NI VSZ RSS MWCHAN STAT TT TIME >> COMMAND PID LWP TT STAT TIME COMMAND >> 0 39143 38949 0 52 0 12368 1064 vnread DL+ 2 0:00.00 >> cp /usr/local/sh 39143 101176 2 DL+ 0:00.00 cp >> /usr/local/share/automake-1.15/compile ./compile >> >> >> (kgdb) thread 473 >> [Switching to thread 473 (Thread 101176)]#0 sched_switch >> (td=0xfffff803320b84b0, newtd=<value optimized out>, flags=<value optimized >> out>) >> at /usr/home/sobomax/projects/freebsd103/sys/kern/sched_ule.c:1945 >> 1945 cpuid = PCPU_GET(cpuid); >> (kgdb) bt >> #0 sched_switch (td=0xfffff803320b84b0, newtd=<value optimized out>, >> flags=<value optimized out>) >> at /usr/home/sobomax/projects/freebsd103/sys/kern/sched_ule.c:1945 >> #1 0xffffffff809364d1 in mi_switch (flags=260, newtd=0x0) at >> /usr/home/sobomax/projects/freebsd103/sys/kern/kern_synch.c:491 >> #2 0xffffffff809761ca in sleepq_wait (wchan=0x0, pri=0) at >> /usr/home/sobomax/projects/freebsd103/sys/kern/subr_sleepqueue.c:618 >> #3 0xffffffff80935ef7 in _sleep (ident=<value optimized out>, >> lock=<value optimized out>, priority=<value optimized out>, wmesg=<value >> optimized out>, >> sbt=<value optimized out>, pr=<value optimized out>, flags=<value >> optimized out>) at >> /usr/home/sobomax/projects/freebsd103/sys/kern/kern_synch.c:255 >> #4 0xffffffff809b7c6e in bwait (bp=0xfffffe03e1012048, pri=<value >> optimized out>, wchan=0xffffffff81069471 "vnread") >> at /usr/home/sobomax/projects/freebsd103/sys/kern/vfs_bio.c:4431 >> #5 0xffffffff80b56663 in vnode_pager_generic_getpages >> (vp=0xfffff802b7e73588, m=0xfffffe0468c4ebe0, bytecount=<value optimized >> out>, >> reqpage=<value optimized out>) at >> /usr/home/sobomax/projects/freebsd103/sys/vm/vnode_pager.c:907 >> #6 0xffffffff80dd7fa7 in VOP_GETPAGES_APV (vop=<value optimized out>, >> a=<value optimized out>) at vnode_if.c:2795 >> #7 0xffffffff80b54a0a in vnode_pager_getpages (object=<value optimized >> out>, m=0xfffffe0468c4ebe0, count=<value optimized out>, reqpage=0) >> at vnode_if.h:1154 >> #8 0xffffffff80b354a1 in vm_fault_hold (map=0xfffff800294c98c0, >> vaddr=34366300160, fault_type=<value optimized out>, fault_flags=0, >> m_hold=0x0) >> at vm_pager.h:127 >> #9 0xffffffff80b34c07 in vm_fault (map=0xfffff800294c98c0, vaddr=<value >> optimized out>, fault_type=1 '\001', fault_flags=0) >> at /usr/home/sobomax/projects/freebsd103/sys/vm/vm_fault.c:273 >> #10 0xffffffff80cbaef5 in trap_pfault (frame=0xfffffe0468c4f040, >> usermode=0) at >> /usr/home/sobomax/projects/freebsd103/sys/amd64/amd64/trap.c:747 >> #11 0xffffffff80cba65d in trap (frame=0xfffffe0468c4f040) at >> /usr/home/sobomax/projects/freebsd103/sys/amd64/amd64/trap.c:447 >> #12 0xffffffff80ca0592 in calltrap () at >> /usr/home/sobomax/projects/freebsd103/sys/amd64/amd64/exception.S:236 >> #13 0xffffffff80cb8b71 in copyin () at >> /usr/home/sobomax/projects/freebsd103/sys/amd64/amd64/support.S:311 >> #14 0xffffffff8097d70f in uiomove_faultflag (cp=<value optimized out>, >> n=<value optimized out>, uio=0xfffffe0468c4f960, nofault=<value optimized >> out>) >> at /usr/home/sobomax/projects/freebsd103/sys/kern/subr_uio.c:253 >> ---Type <return> to continue, or q <return> to quit--- >> #15 0xffffffff819f799c in dmu_write_uio_dnode () from /boot/kernel/zfs.ko >> #16 0xffffffff819f78b2 in dmu_write_uio_dbuf () from /boot/kernel/zfs.ko >> #17 0xffffffff81a91a07 in zfs_freebsd_write () from /boot/kernel/zfs.ko >> #18 0xffffffff80dd6219 in VOP_WRITE_APV (vop=<value optimized out>, >> a=<value optimized out>) at vnode_if.c:999 >> #19 0xffffffff808730b2 in null_bypass (ap=0xfffffe0468c4f7d0) at >> /usr/home/sobomax/projects/freebsd103/sys/fs/nullfs/null_vnops.c:280 >> #20 0xffffffff80dd621f in VOP_WRITE_APV (vop=<value optimized out>, >> a=<value optimized out>) at vnode_if.c:1001 >> #21 0xffffffff809dea28 in vn_write (fp=0xfffff8004bc0ddc0, >> uio=0xfffffe0468c4f960, active_cred=0x1ca5, flags=916, >> td=0xfffffe00006a60d0) >> at vnode_if.h:413 >> #22 0xffffffff809dad6b in vn_io_fault (fp=0xfffff8004bc0ddc0, >> uio=0xfffffe0468c4f960, active_cred=0x1ca5, flags=0, td=0xfffffe00006a60d0) >> at /usr/home/sobomax/projects/freebsd103/sys/kern/vfs_vnops.c:1225 >> #23 0xffffffff80981937 in dofilewrite (td=0xfffff803320b84b0, fd=4, >> fp=0xfffff8004bc0ddc0, auio=0xfffffe0468c4f960, offset=<value optimized >> out>, >> flags=0) at file.h:305 >> #24 0xffffffff80981668 in kern_writev (td=0xfffff803320b84b0, fd=4, >> auio=0xfffffe0468c4f960) >> at /usr/home/sobomax/projects/freebsd103/sys/kern/sys_generic.c:481 >> #25 0xffffffff809815f3 in sys_write (td=<value optimized out>, uap=<value >> optimized out>) >> at /usr/home/sobomax/projects/freebsd103/sys/kern/sys_generic.c:396 >> #26 0xffffffff80cbb559 in amd64_syscall (td=0xfffff803320b84b0, traced=0) >> at subr_syscall.c:141 >> #27 0xffffffff80ca087b in Xfast_syscall () at >> /usr/home/sobomax/projects/freebsd103/sys/amd64/amd64/exception.S:396 >> #28 0x0000000800968f5a in ?? () >> >> >> On Wed, Mar 2, 2016 at 1:12 AM, Maxim Sobolev <sobomax@freebsd.org> >> wrote: >> >>> Hi, I've encountered cp(1) process stuck in the vnread state on one of >>> my build machines that got recently upgraded to 10.3. >>> >>> 0 79596 1 0 20 0 17092 1396 wait I 1 >>> 0:00.00 /bin/sh /usr/local/bin/autoreconf -f -i >>> 0 79602 79596 0 52 0 41488 9036 wait I 1 >>> 0:00.07 /usr/local/bin/perl -w /usr/local/bin/autoreconf-2.69 -f -i >>> 0 79639 79602 0 72 0 0 0 - Z 1 >>> 0:00.27 <defunct> >>> 0 79762 79602 0 20 0 17092 1396 wait I 1 >>> 0:00.00 /bin/sh /usr/local/bin/automake --add-missing --copy --force-missing >>> 0 79768 79762 0 52 0 49736 13936 wait I 1 >>> 0:00.11 /usr/local/bin/perl -w /usr/local/bin/automake-1.15 --add-missing >>> --copy --force-missing >>> 0 79962 79768 0 20 0 12368 1024 vnread DL 1 >>> 0:00.00 cp /usr/local/share/automake-1.15/compile ./compile >>> >>> I am not sure if it's related to that OS version upgrade, but I have not >>> seen any such issues on the same machine in 2-3 years running essentially >>> the same build process with version 9.x, 10.0, 10.1 and 10.2. >>> >>> $ uname -a >>> FreeBSD van01.sippysoft.com 10.3-PRERELEASE FreeBSD 10.3-PRERELEASE #1 >>> 80de3e2(master)-dirty: Tue Feb 2 12:19:57 PST 2016 >>> sobomax@abc.sippysoft.com:/usr/obj/usr/home/sobomax/projects/freebsd103/sys/ABC >>> amd64 >>> >>> The kernel stack trace is: >>> >>> (kgdb) thread 360 >>> [Switching to thread 360 (Thread 100515)]#0 0xffffffff8095244e in >>> sched_switch () >>> (kgdb) bt >>> #0 0xffffffff8095244e in sched_switch () >>> #1 0xffffffff809313b1 in mi_switch () >>> #2 0xffffffff8097089a in sleepq_wait () >>> #3 0xffffffff80930dd7 in _sleep () >>> #4 0xffffffff809b230e in bwait () >>> #5 0xffffffff80b511f3 in vnode_pager_generic_getpages () >>> #6 0xffffffff80dd1607 in VOP_GETPAGES_APV () >>> #7 0xffffffff80b4f59a in vnode_pager_getpages () >>> #8 0xffffffff80b30031 in vm_fault_hold () >>> #9 0xffffffff80b2f797 in vm_fault () >>> #10 0xffffffff80cb5a75 in trap_pfault () >>> #11 0xffffffff80cb51dd in trap () >>> #12 0xffffffff80c9b122 in calltrap () >>> #13 0xffffffff80cb36f1 in copyin () >>> #14 0xffffffff80977ddf in uiomove_faultflag () >>> >>> The FS stack configuration is somewhat unique, so I am not sure if I am >>> hitting some rare race condition or lock ordering issues specific to that. >>> It's basically ZFS (ZRAID) on top of pair or SATA SSDs with big file on >>> that FS attached via md(4) and UFS2 on that md(4). The build itself runs in >>> chroot with that UFS2 fs as its primary root. >>> >>> Just maybe additional bit of info, attempting to list the directory with >>> that UFS image also got my bash process stuck in "zfs" state, backtrace >>> from that is: >>> >>> (kgdb) thread 353 >>> [Switching to thread 353 (Thread 100508)]#0 0xffffffff8095244e in >>> sched_switch () >>> (kgdb) bt >>> #0 0xffffffff8095244e in sched_switch () >>> #1 0xffffffff809313b1 in mi_switch () >>> #2 0xffffffff8097089a in sleepq_wait () >>> #3 0xffffffff809069ad in sleeplk () >>> #4 0xffffffff809060e0 in __lockmgr_args () >>> #5 0xffffffff809b8b7c in vop_stdlock () >>> #6 0xffffffff80dd0a3b in VOP_LOCK1_APV () >>> #7 0xffffffff809d6d23 in _vn_lock () >>> #8 0xffffffff81a8c9cd in ?? () >>> #9 0x0000000000000000 in ?? () >>> >>> >>> >> >> >> -- >> Maksym Sobolyev >> Sippy Software, Inc. >> Internet Telephony (VoIP) Experts >> Tel (Canada): +1-778-783-0474 >> Tel (Toll-Free): +1-855-747-7779 >> Fax: +1-866-857-6942 >> Web: http://www.sippysoft.com >> MSN: sales@sippysoft.com >> Skype: SippySoft >> > > > > -- > Maksym Sobolyev > Sippy Software, Inc. > Internet Telephony (VoIP) Experts > Tel (Canada): +1-778-783-0474 > Tel (Toll-Free): +1-855-747-7779 > Fax: +1-866-857-6942 > Web: http://www.sippysoft.com > MSN: sales@sippysoft.com > Skype: SippySoft >
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