Date: Mon, 26 Aug 2019 22:15:01 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Cy Schubert <Cy.Schubert@cschubert.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r351472 - head/sys/fs/nullfs Message-ID: <CAGudoHHGLguWZZMh%2BTOCBwANKKp7-6z5JvP1NgRo3jAr4vZ%2BPw@mail.gmail.com> In-Reply-To: <C3B4FE65-FC10-4248-AB00-0E30532C77EB@cschubert.com> References: <201908250513.x7P5DFFx017824@repo.freebsd.org> <6C6BF3A4-DC07-4D9A-9A5F-FA075BF535A8@cschubert.com> <201908261411.x7QEBMWi075354@slippy.cwsent.com> <A961554B-2B0B-4382-BA73-D69FC0129D0B@cschubert.com> <C3B4FE65-FC10-4248-AB00-0E30532C77EB@cschubert.com>
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Does this do the trick for you? https://people.freebsd.org/~mjg/vop_unlock-interlock.diff On 8/26/19, Cy Schubert <Cy.Schubert@cschubert.com> wrote: > On August 26, 2019 8:40:50 AM PDT, Cy Schubert <Cy.Schubert@cschubert.com> > wrote: >>On August 26, 2019 7:11:22 AM PDT, Cy Schubert >><Cy.Schubert@cschubert.com> wrote: >>>In message <6C6BF3A4-DC07-4D9A-9A5F-FA075BF535A8@cschubert.com>, Cy >>>Schubert wr >>>ites: >>>> On August 24, 2019 10:13:15 PM PDT, Mateusz Guzik <mjg@FreeBSD.org> >>>wrote: >>>> >Author: mjg >>>> >Date: Sun Aug 25 05:13:15 2019 >>>> >New Revision: 351472 >>>> >URL: https://svnweb.freebsd.org/changeset/base/351472 >>>> > >>>> >Log: >>>> > nullfs: reduce areas protected by vnode interlock >>>> > >>>> >Some places only take the interlock to hold the vnode, which was a >>>> >requiremnt >>>> >before they started being manipulated with atomics. Use the newly >>>> >introduced >>>> > vholdnz to bump the count. >>>> > >>>> > Reviewed by: kib >>>> > Tested by: pho >>>> > Sponsored by: The FreeBSD Foundation >>>> > Differential Revision: https://reviews.freebsd.org/D21358 >>>> > >>>> >Modified: >>>> > head/sys/fs/nullfs/null_vnops.c >>>> > >>>> >Modified: head/sys/fs/nullfs/null_vnops.c >>>> >>>>============================================================================ >>>> == >>>> >--- head/sys/fs/nullfs/null_vnops.c Sun Aug 25 05:11:43 >>2019 (r35147 >>>> 1) >>>> >+++ head/sys/fs/nullfs/null_vnops.c Sun Aug 25 05:13:15 >>2019 (r35147 >>>> 2) >>>> >@@ -668,7 +668,7 @@ null_lock(struct vop_lock1_args *ap) >>>> > * We prevent it from being recycled by holding the vnode >>>> > * here. >>>> > */ >>>> >- vholdl(lvp); >>>> >+ vholdnz(lvp); >>>> > error = VOP_LOCK(lvp, flags); >>>> > >>>> > /* >>>> >@@ -710,31 +710,16 @@ static int >>>> > null_unlock(struct vop_unlock_args *ap) >>>> > { >>>> > struct vnode *vp = ap->a_vp; >>>> >- int flags = ap->a_flags; >>>> >- int mtxlkflag = 0; >>>> > struct null_node *nn; >>>> > struct vnode *lvp; >>>> > int error; >>>> > >>>> >- if ((flags & LK_INTERLOCK) != 0) >>>> >- mtxlkflag = 1; >>>> >- else if (mtx_owned(VI_MTX(vp)) == 0) { >>>> >- VI_LOCK(vp); >>>> >- mtxlkflag = 2; >>>> >- } >>>> > nn = VTONULL(vp); >>>> > if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) { >>>> >- VI_LOCK_FLAGS(lvp, MTX_DUPOK); >>>> >- flags |= LK_INTERLOCK; >>>> >- vholdl(lvp); >>>> >- VI_UNLOCK(vp); >>>> >- error = VOP_UNLOCK(lvp, flags); >>>> >+ vholdnz(lvp); >>>> >+ error = VOP_UNLOCK(lvp, 0); >>>> > vdrop(lvp); >>>> >- if (mtxlkflag == 0) >>>> >- VI_LOCK(vp); >>>> > } else { >>>> >- if (mtxlkflag == 2) >>>> >- VI_UNLOCK(vp); >>>> > error = vop_stdunlock(ap); >>>> > } >>>> > >>>> >@@ -845,10 +830,8 @@ null_getwritemount(struct >>>vop_getwritemount_args >>>> >*ap) >>>> > VI_LOCK(vp); >>>> > xp = VTONULL(vp); >>>> > if (xp && (lowervp = xp->null_lowervp)) { >>>> >- VI_LOCK_FLAGS(lowervp, MTX_DUPOK); >>>> >+ vholdnz(lowervp); >>>> > VI_UNLOCK(vp); >>>> >- vholdl(lowervp); >>>> >- VI_UNLOCK(lowervp); >>>> > VOP_GETWRITEMOUNT(lowervp, ap->a_mpp); >>>> > vdrop(lowervp); >>>> > } else { >>>> >>>> Hi mjg@, >>>> >>>> This causes trap 12 a few seconds after mountlate during boot. >>>Reverting this >>>> commit allowed it to boot. >>>> >>>> Sorry for no backtrace. I managed to >>>> revert and test just prior to rushing out to catch the bus, with no >>>time to >>>> craft a proper email. I'll post the backtrace when I arrive at work. >>> >>>Hi mjg@, >>> >>>The gory details below. Don't be fooled by the panic when yppasswd is >>>started. I was able to reproduce this panic in single user by simply >>>mounting and using a nullfs. >>> >>>kernel trap 12 with interrupts disabled >>> >>> >>>Fatal trap 12: page fault while in kernel mode >>>cpuid = 0; apic id = 00 >>>fault virtual address = 0xc >>>fault code = supervisor read data, page not present >>>instruction pointer = 0x20:0xffffffff806f0633 >>>stack pointer = 0x28:0xfffffe004b3fa7c0 >>>frame pointer = 0x28:0xfffffe004b3fa7e0 >>>code segment = base 0x0, limit 0xfffff, type 0x1b >>> = DPL 0, pres 1, long 1, def32 0, gran 1 >>>processor eflags = resume, IOPL = 0 >>>current process = 26 (syncer) >>>trap number = 12 >>>panic: page fault >>>cpuid = 0 >>>time = 1566821203 >>>KDB: stack backtrace: >>>db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame >>>0xfffffe004b3fa470 >>>vpanic() at vpanic+0x19d/frame 0xfffffe004b3fa4c0 >>>panic() at panic+0x43/frame 0xfffffe004b3fa520 >>>trap_fatal() at trap_fatal+0x39c/frame 0xfffffe004b3fa580 >>>trap_pfault() at trap_pfault+0x49/frame 0xfffffe004b3fa5e0 >>>trap() at trap+0x29d/frame 0xfffffe004b3fa6f0 >>>calltrap() at calltrap+0x8/frame 0xfffffe004b3fa6f0 >>>--- trap 0xc, rip = 0xffffffff806f0633, rsp = 0xfffffe004b3fa7c0, rbp >>= >>>0xfffffe004b3fa7e0 --- >>>propagate_priority() at propagate_priority+0x153/frame >>>0xfffffe004b3fa7e0 >>>turnstile_wait() at turnstile_wait+0x32b/frame 0xfffffe004b3fa830 >>>__mtx_lock_sleep() at __mtx_lock_sleep+0x191/frame 0xfffffe004b3fa8c0 >>>mnt_vnode_next_active() at mnt_vnode_next_active+0x2cb/frame >>>0xfffffe004b3fa920 >>>vfs_msync() at vfs_msync+0x266/frame 0xfffffe004b3fa980 >>>sync_fsync() at sync_fsync+0xe6/frame 0xfffffe004b3fa9c0 >>>VOP_FSYNC_APV() at VOP_FSYNC_APV+0x56/frame 0xfffffe004b3fa9e0 >>>sched_sync() at sched_sync+0x379/frame 0xfffffe004b3faa70 >>>fork_exit() at fork_exit+0x83/frame 0xfffffe004b3faab0 >>>fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe004b3faab0 >>>--- trap 0, rip = 0, rsp = 0, rbp = 0 --- >>>Uptime: 3m25s >>>Dumping 921 out of 7974 >>>MB:..2%..11%..21%..32%..42%..51%..61%..72%..82%..91% >>> >>>__curthread () at /opt/src/svn-current/sys/amd64/include/pcpu.h:246 >>>246 __asm("movq %%gs:%P1,%0" : "=r" (td) : "n" >>>(OFFSETOF_CURTHREAD)); >>>(kgdb) #0 __curthread () at >>>/opt/src/svn-current/sys/amd64/include/pcpu.h:246 >>>#1 doadump (textdump=1) at >>>/opt/src/svn-current/sys/kern/kern_shutdown.c:392 >>>#2 0xffffffff8068aead in kern_reboot (howto=260) >>> at /opt/src/svn-current/sys/kern/kern_shutdown.c:479 >>>#3 0xffffffff8068b369 in vpanic (fmt=<optimized out>, ap=<optimized >>>out>) >>> at /opt/src/svn-current/sys/kern/kern_shutdown.c:905 >>>#4 0xffffffff8068b163 in panic (fmt=<unavailable>) >>> at /opt/src/svn-current/sys/kern/kern_shutdown.c:832 >>>#5 0xffffffff80a11c2c in trap_fatal (frame=0xfffffe004b3fa700, >>eva=12) >>> at /opt/src/svn-current/sys/amd64/amd64/trap.c:943 >>>#6 0xffffffff80a11c79 in trap_pfault (frame=0xfffffe004b3fa700, >>>usermode=0) >>> at /opt/src/svn-current/sys/amd64/amd64/trap.c:767 >>>#7 0xffffffff80a1126d in trap (frame=0xfffffe004b3fa700) >>> at /opt/src/svn-current/sys/amd64/amd64/trap.c:443 >>>#8 <signal handler called> >>>#9 propagate_priority (td=0xfffff8003e43b000) >>> at /opt/src/svn-current/sys/kern/subr_turnstile.c:279 >>>#10 0xffffffff806f13db in turnstile_wait (ts=0xfffff8000258a780, >>> owner=<optimized out>, queue=-512) >>> at /opt/src/svn-current/sys/kern/subr_turnstile.c:785 >>>#11 0xffffffff80669271 in __mtx_lock_sleep (c=0xfffff80132e4ebf0, >>> v=<optimized out>) at >>/opt/src/svn-current/sys/kern/kern_mutex.c:654 >>>#12 0xffffffff80767b1b in mnt_vnode_next_active_relock ( >>> mvp=0xfffff80002449800, mp=0xfffff80132d1e000, >>vp=0xfffff80132e4eb40) >>> at /opt/src/svn-current/sys/kern/vfs_subr.c:5590 >>>#13 mnt_vnode_next_active (mvp=<optimized out>, mp=0xfffff80132d1e000) >>> at /opt/src/svn-current/sys/kern/vfs_subr.c:5649 >>>#14 0xffffffff80766206 in __mnt_vnode_next_active >>>(mvp=0xfffff80002449800, >>> mp=<optimized out>) at >>/opt/src/svn-current/sys/kern/vfs_subr.c:5682 >>>#15 vfs_msync (mp=0xfffff80132d1e000, flags=2) >>> at /opt/src/svn-current/sys/kern/vfs_subr.c:4238 >>>#16 0xffffffff8076b4a6 in sync_fsync (ap=<optimized out>) >>> at /opt/src/svn-current/sys/kern/vfs_subr.c:4468 >>>#17 0xffffffff80a7be46 in VOP_FSYNC_APV ( >>> vop=0xffffffff80cb4120 <sync_vnodeops>, a=0xfffffe004b3faa08) >>> at vnode_if.c:1312 >>>#18 0xffffffff80769319 in VOP_FSYNC (vp=<optimized out>, waitfor=3, >>> td=0xfffff800061dc5a0) at ./vnode_if.h:549 >>>#19 sync_vnode (bo=<optimized out>, td=0xfffff800061dc5a0, >>> slp=<optimized out>) at >>/opt/src/svn-current/sys/kern/vfs_subr.c:2316 >>>#20 sched_sync () at /opt/src/svn-current/sys/kern/vfs_subr.c:2418 >>>#21 0xffffffff80647e33 in fork_exit (callout=0xffffffff80768fa0 >>><sched_sync>, >>> arg=0x0, frame=0xfffffe004b3faac0) >>> at /opt/src/svn-current/sys/kern/kern_fork.c:1045 >>>#22 <signal handler called> >>> >>> >>>dmesg output: >>> >>>Updating motd:. >>>Mounting late filesystems:. >>>Starting nscd. >>>Security policy loaded: MAC/ntpd (mac_ntpd) >>>Starting ntpd. >>>Starting yppasswdd. >>>kernel trap 12 with interrupts disabled >>> >>> >>>Fatal trap 12: page fault while in kernel mode >>>cpuid = 0; apic id = 00 >>>fault virtual address = 0xc >>>fault code = supervisor read data, page not present >>>instruction pointer = 0x20:0xffffffff806f0633 >>>stack pointer = 0x28:0xfffffe004b7fa7c0 >>>frame pointer = 0x28:0xfffffe004b7fa7e0 >>>code segment = base 0x0, limit 0xfffff, type 0x1b >>> = DPL 0, pres 1, long 1, def32 0, gran 1 >>>processor eflags = resume, IOPL = 0 >>>current process = 26 (syncer) >>>trap number = 12 >>>panic: page fault >>>cpuid = 0 >>>time = 1566820700 >>>KDB: stack backtrace: >>>db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame >>>0xfffffe004b7fa470 >>>vpanic() at vpanic+0x19d/frame 0xfffffe004b7fa4c0 >>>panic() at panic+0x43/frame 0xfffffe004b7fa520 >>>trap_fatal() at trap_fatal+0x39c/frame 0xfffffe004b7fa580 >>>trap_pfault() at trap_pfault+0x49/frame 0xfffffe004b7fa5e0 >>>trap() at trap+0x29d/frame 0xfffffe004b7fa6f0 >>>calltrap() at calltrap+0x8/frame 0xfffffe004b7fa6f0 >>>--- trap 0xc, rip = 0xffffffff806f0633, rsp = 0xfffffe004b7fa7c0, rbp >>= >>>0xfffffe004b7fa7e0 --- >>>propagate_priority() at propagate_priority+0x153/frame >>>0xfffffe004b7fa7e0 >>>turnstile_wait() at turnstile_wait+0x32b/frame 0xfffffe004b7fa830 >>>__mtx_lock_sleep() at __mtx_lock_sleep+0x191/frame 0xfffffe004b7fa8c0 >>>mnt_vnode_next_active() at mnt_vnode_next_active+0x2cb/frame >>>0xfffffe004b7fa920 >>>vfs_msync() at vfs_msync+0x266/frame 0xfffffe004b7fa980 >>>sync_fsync() at sync_fsync+0xe6/frame 0xfffffe004b7fa9c0 >>>--- trap 0, rip = 0, rsp = 0, rbp = 0 --- >>>Uptime: 1m38s >>>Dumping 810 out of 7974 >>>MB:..2%..12%..22%..32%..42%..52%..62%..72%..81%..91%---<<BOOT>>--- >> >>This may be a simple case of increasing the kernel stack. I'll try this >>at noon. > > Increasing kernel stack pages from 8 to 20 still results in the panic. > > > -- > Pardon the typos and autocorrect, small keyboard in use. > Cheers, > Cy Schubert <Cy.Schubert@cschubert.com> > FreeBSD UNIX: <cy@FreeBSD.org> Web: http://www.FreeBSD.org > > The need of the many outweighs the greed of the few. > -- Mateusz Guzik <mjguzik gmail.com>
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