svn commit: r351472 - head/sys/fs/nullfs
Cy Schubert
Cy.Schubert at cschubert.com
Mon Aug 26 18:57:14 UTC 2019
On August 26, 2019 8:40:50 AM PDT, Cy Schubert <Cy.Schubert at cschubert.com> wrote:
>On August 26, 2019 7:11:22 AM PDT, Cy Schubert
><Cy.Schubert at cschubert.com> wrote:
>>In message <6C6BF3A4-DC07-4D9A-9A5F-FA075BF535A8 at cschubert.com>, Cy
>>Schubert wr
>>ites:
>>> On August 24, 2019 10:13:15 PM PDT, Mateusz Guzik <mjg at 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 at cschubert.com>
FreeBSD UNIX: <cy at FreeBSD.org> Web: http://www.FreeBSD.org
The need of the many outweighs the greed of the few.
More information about the svn-src-head
mailing list