Date: Mon, 26 Aug 2019 08:40:50 -0700 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Mateusz Guzik <mjg@FreeBSD.org> 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: <A961554B-2B0B-4382-BA73-D69FC0129D0B@cschubert.com> In-Reply-To: <201908261411.x7QEBMWi075354@slippy.cwsent.com> References: <201908250513.x7P5DFFx017824@repo.freebsd.org> <6C6BF3A4-DC07-4D9A-9A5F-FA075BF535A8@cschubert.com> <201908261411.x7QEBMWi075354@slippy.cwsent.com>
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On August 26, 2019 7:11:22 AM PDT, Cy Schubert <Cy=2ESchubert@cschubert=2Ec= om> wrote: >In message <6C6BF3A4-DC07-4D9A-9A5F-FA075BF535A8@cschubert=2Ecom>, Cy >Schubert wr >ites: >> On August 24, 2019 10:13:15 PM PDT, Mateusz Guzik <mjg@FreeBSD=2Eorg> >wrote: >> >Author: mjg >> >Date: Sun Aug 25 05:13:15 2019 >> >New Revision: 351472 >> >URL: https://svnweb=2Efreebsd=2Eorg/changeset/base/351472 >> > >> >Log: >> > nullfs: reduce areas protected by vnode interlock >> > =20 >> >Some places only take the interlock to hold the vnode, which was a >> >requiremnt >> >before they started being manipulated with atomics=2E Use the newly >> >introduced >> > vholdnz to bump the count=2E >> > =20 >> > Reviewed by: kib >> > Tested by: pho >> > Sponsored by: The FreeBSD Foundation >> > Differential Revision: https://reviews=2Efreebsd=2Eorg/D21358 >> > >> >Modified: >> > head/sys/fs/nullfs/null_vnops=2Ec >> > >> >Modified: head/sys/fs/nullfs/null_vnops=2Ec >> >>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D >> =3D=3D >> >--- head/sys/fs/nullfs/null_vnops=2Ec Sun Aug 25 05:11:43 2019 (r35147 >> 1) >> >+++ head/sys/fs/nullfs/null_vnops=2Ec 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=2E >> > */ >> >- vholdl(lvp); >> >+ vholdnz(lvp); >> > error =3D VOP_LOCK(lvp, flags); >> >=20 >> > /* >> >@@ -710,31 +710,16 @@ static int >> > null_unlock(struct vop_unlock_args *ap) >> > { >> > struct vnode *vp =3D ap->a_vp; >> >- int flags =3D ap->a_flags; >> >- int mtxlkflag =3D 0; >> > struct null_node *nn; >> > struct vnode *lvp; >> > int error; >> >=20 >> >- if ((flags & LK_INTERLOCK) !=3D 0) >> >- mtxlkflag =3D 1; >> >- else if (mtx_owned(VI_MTX(vp)) =3D=3D 0) { >> >- VI_LOCK(vp); >> >- mtxlkflag =3D 2; >> >- } >> > nn =3D VTONULL(vp); >> > if (nn !=3D NULL && (lvp =3D NULLVPTOLOWERVP(vp)) !=3D NULL) { >> >- VI_LOCK_FLAGS(lvp, MTX_DUPOK); >> >- flags |=3D LK_INTERLOCK; >> >- vholdl(lvp); >> >- VI_UNLOCK(vp); >> >- error =3D VOP_UNLOCK(lvp, flags); >> >+ vholdnz(lvp); >> >+ error =3D VOP_UNLOCK(lvp, 0); >> > vdrop(lvp); >> >- if (mtxlkflag =3D=3D 0) >> >- VI_LOCK(vp); >> > } else { >> >- if (mtxlkflag =3D=3D 2) >> >- VI_UNLOCK(vp); >> > error =3D vop_stdunlock(ap); >> > } >> >=20 >> >@@ -845,10 +830,8 @@ null_getwritemount(struct >vop_getwritemount_args >> >*ap) >> > VI_LOCK(vp); >> > xp =3D VTONULL(vp); >> > if (xp && (lowervp =3D 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=2E >Reverting this >> commit allowed it to boot=2E >> >> Sorry for no backtrace=2E I managed to=20 >> revert and test just prior to rushing out to catch the bus, with no >time to=20 >> craft a proper email=2E I'll post the backtrace when I arrive at work= =2E > >Hi mjg@, > >The gory details below=2E Don't be fooled by the panic when yppasswd is >started=2E I was able to reproduce this panic in single user by simply >mounting and using a nullfs=2E > >kernel trap 12 with interrupts disabled > > >Fatal trap 12: page fault while in kernel mode >cpuid =3D 0; apic id =3D 00 >fault virtual address =3D 0xc >fault code =3D supervisor read data, page not present >instruction pointer =3D 0x20:0xffffffff806f0633 >stack pointer =3D 0x28:0xfffffe004b3fa7c0 >frame pointer =3D 0x28:0xfffffe004b3fa7e0 >code segment =3D base 0x0, limit 0xfffff, type 0x1b > =3D DPL 0, pres 1, long 1, def32 0, gran 1 >processor eflags =3D resume, IOPL =3D 0 >current process =3D 26 (syncer) >trap number =3D 12 >panic: page fault >cpuid =3D 0 >time =3D 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 =3D 0xffffffff806f0633, rsp =3D 0xfffffe004b3fa7c0, rbp= =3D >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 =3D 0, rsp =3D 0, rbp =3D 0 --- >Uptime: 3m25s >Dumping 921 out of 7974 >MB:=2E=2E2%=2E=2E11%=2E=2E21%=2E=2E32%=2E=2E42%=2E=2E51%=2E=2E61%=2E=2E72= %=2E=2E82%=2E=2E91% > >__curthread () at /opt/src/svn-current/sys/amd64/include/pcpu=2Eh:246 >246 __asm("movq %%gs:%P1,%0" : "=3Dr" (td) : "n" >(OFFSETOF_CURTHREAD)); >(kgdb) #0 __curthread () at >/opt/src/svn-current/sys/amd64/include/pcpu=2Eh:246 >#1 doadump (textdump=3D1) at >/opt/src/svn-current/sys/kern/kern_shutdown=2Ec:392 >#2 0xffffffff8068aead in kern_reboot (howto=3D260) > at /opt/src/svn-current/sys/kern/kern_shutdown=2Ec:479 >#3 0xffffffff8068b369 in vpanic (fmt=3D<optimized out>, ap=3D<optimized >out>) > at /opt/src/svn-current/sys/kern/kern_shutdown=2Ec:905 >#4 0xffffffff8068b163 in panic (fmt=3D<unavailable>) > at /opt/src/svn-current/sys/kern/kern_shutdown=2Ec:832 >#5 0xffffffff80a11c2c in trap_fatal (frame=3D0xfffffe004b3fa700, eva=3D1= 2) > at /opt/src/svn-current/sys/amd64/amd64/trap=2Ec:943 >#6 0xffffffff80a11c79 in trap_pfault (frame=3D0xfffffe004b3fa700, >usermode=3D0) > at /opt/src/svn-current/sys/amd64/amd64/trap=2Ec:767 >#7 0xffffffff80a1126d in trap (frame=3D0xfffffe004b3fa700) > at /opt/src/svn-current/sys/amd64/amd64/trap=2Ec:443 >#8 <signal handler called> >#9 propagate_priority (td=3D0xfffff8003e43b000) > at /opt/src/svn-current/sys/kern/subr_turnstile=2Ec:279 >#10 0xffffffff806f13db in turnstile_wait (ts=3D0xfffff8000258a780,=20 > owner=3D<optimized out>, queue=3D-512) > at /opt/src/svn-current/sys/kern/subr_turnstile=2Ec:785 >#11 0xffffffff80669271 in __mtx_lock_sleep (c=3D0xfffff80132e4ebf0,=20 > v=3D<optimized out>) at /opt/src/svn-current/sys/kern/kern_mutex=2Ec:6= 54 >#12 0xffffffff80767b1b in mnt_vnode_next_active_relock ( > mvp=3D0xfffff80002449800, mp=3D0xfffff80132d1e000, vp=3D0xfffff80132e4e= b40) > at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:5590 >#13 mnt_vnode_next_active (mvp=3D<optimized out>, mp=3D0xfffff80132d1e000= ) > at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:5649 >#14 0xffffffff80766206 in __mnt_vnode_next_active >(mvp=3D0xfffff80002449800,=20 > mp=3D<optimized out>) at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:56= 82 >#15 vfs_msync (mp=3D0xfffff80132d1e000, flags=3D2) > at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:4238 >#16 0xffffffff8076b4a6 in sync_fsync (ap=3D<optimized out>) > at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:4468 >#17 0xffffffff80a7be46 in VOP_FSYNC_APV ( > vop=3D0xffffffff80cb4120 <sync_vnodeops>, a=3D0xfffffe004b3faa08) > at vnode_if=2Ec:1312 >#18 0xffffffff80769319 in VOP_FSYNC (vp=3D<optimized out>, waitfor=3D3,= =20 > td=3D0xfffff800061dc5a0) at =2E/vnode_if=2Eh:549 >#19 sync_vnode (bo=3D<optimized out>, td=3D0xfffff800061dc5a0,=20 > slp=3D<optimized out>) at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:23= 16 >#20 sched_sync () at /opt/src/svn-current/sys/kern/vfs_subr=2Ec:2418 >#21 0xffffffff80647e33 in fork_exit (callout=3D0xffffffff80768fa0 ><sched_sync>,=20 > arg=3D0x0, frame=3D0xfffffe004b3faac0) > at /opt/src/svn-current/sys/kern/kern_fork=2Ec:1045 >#22 <signal handler called> > > >dmesg output: > >Updating motd:=2E >Mounting late filesystems:=2E >Starting nscd=2E >Security policy loaded: MAC/ntpd (mac_ntpd) >Starting ntpd=2E >Starting yppasswdd=2E >kernel trap 12 with interrupts disabled > > >Fatal trap 12: page fault while in kernel mode >cpuid =3D 0; apic id =3D 00 >fault virtual address =3D 0xc >fault code =3D supervisor read data, page not present >instruction pointer =3D 0x20:0xffffffff806f0633 >stack pointer =3D 0x28:0xfffffe004b7fa7c0 >frame pointer =3D 0x28:0xfffffe004b7fa7e0 >code segment =3D base 0x0, limit 0xfffff, type 0x1b > =3D DPL 0, pres 1, long 1, def32 0, gran 1 >processor eflags =3D resume, IOPL =3D 0 >current process =3D 26 (syncer) >trap number =3D 12 >panic: page fault >cpuid =3D 0 >time =3D 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 =3D 0xffffffff806f0633, rsp =3D 0xfffffe004b7fa7c0, rbp= =3D >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 =3D 0, rsp =3D 0, rbp =3D 0 --- >Uptime: 1m38s >Dumping 810 out of 7974 >MB:=2E=2E2%=2E=2E12%=2E=2E22%=2E=2E32%=2E=2E42%=2E=2E52%=2E=2E62%=2E=2E72= %=2E=2E81%=2E=2E91%---<<BOOT>>--- This may be a simple case of increasing the kernel stack=2E I'll try this = at noon=2E --=20 Pardon the typos and autocorrect, small keyboard in use=2E Cheers, Cy Schubert <Cy=2ESchubert@cschubert=2Ecom> FreeBSD UNIX: <cy@FreeBSD=2Eorg> Web: http://www=2EFreeBSD=2Eorg The need of the many outweighs the greed of the few=2E
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