svn commit: r351472 - head/sys/fs/nullfs
Cy Schubert
Cy.Schubert at cschubert.com
Mon Aug 26 15:41:21 UTC 2019
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.
--
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-all
mailing list