svn commit: r363069 - head/sys/kern

[Peter Holm]

On Fri, Jul 10, 2020 at 11:25:52AM +0200, Mateusz Guzik wrote:
> On 7/10/20, Mateusz Guzik <mjguzik at gmail.com> wrote:
> > On 7/10/20, Peter Holm <pho at freebsd.org> wrote:
> >> On Fri, Jul 10, 2020 at 06:47:58AM +0000, Mateusz Guzik wrote:
> >>> Author: mjg
> >>> Date: Fri Jul 10 06:47:58 2020
> >>> New Revision: 363069
> >>> URL: https://svnweb.freebsd.org/changeset/base/363069
> >>>
> >>> Log:
> >>>   vfs: depessimize getfsstat when only the count is requested
> >>>
> >>>   This avoids relocking mountlist_mtx for each entry.
> >>>
> >>> Modified:
> >>>   head/sys/kern/vfs_syscalls.c
> >>>
> >>> Modified: head/sys/kern/vfs_syscalls.c
> >>> ==============================================================================
> >>> --- head/sys/kern/vfs_syscalls.c	Fri Jul 10 06:46:42 2020	(r363068)
> >>
> >> Could this one be yours?
> >>
> >> 20200710 09:46:31 all (267/723): procfs.sh
> >> panic: lock (sleep mutex) mountlist not locked @ kern/vfs_syscalls.c:561
> >> cpuid = 4
> >> time = 1594367192
> >> KDB: stack backtrace:
> >> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> >> 0xfffffe00377a6910
> >> vpanic() at vpanic+0x182/frame 0xfffffe00377a6960
> >> panic() at panic+0x43/frame 0xfffffe00377a69c0
> >> witness_unlock() at witness_unlock+0x147/frame 0xfffffe00377a6a00
> >> __mtx_unlock_flags() at __mtx_unlock_flags+0x4d/frame 0xfffffe00377a6a30
> >> kern_getfsstat() at kern_getfsstat+0x40b/frame 0xfffffe00377a6ab0
> >> sys_getfsstat() at sys_getfsstat+0x22/frame 0xfffffe00377a6ad0
> >> amd64_syscall() at amd64_syscall+0x159/frame 0xfffffe00377a6bf0
> >> fast_syscall_common() at fast_syscall_common+0x101/frame
> >> 0xfffffe00377a6bf0
> >> --- syscall (557, FreeBSD ELF64, sys_getfsstat), rip = 0x80032db1a, rsp =
> >> 0x7fffffffd738, rbp = 0x7fffffffd790 ---
> >> KDB: enter: panic
> >>
> >> https://people.freebsd.org/~pho/stress/log/mjguzik030.txt
> >>
> >
> > Does this fix it for you?
> >
> > diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
> > index f37a54809e24..2caf09f3412c 100644
> > --- a/sys/kern/vfs_syscalls.c
> > +++ b/sys/kern/vfs_syscalls.c
> > @@ -551,7 +551,7 @@ kern_getfsstat(struct thread *td, struct statfs
> > **buf, size_t bufsize,
> >
> >                 if (count == maxcount) {
> >                         vfs_unbusy(mp);
> > -                       break;
> > +                       goto out;
> >                 }
> >
> >                 mtx_lock(&mountlist_mtx);
> >
> 
> Reproduced and verified the above fixes it, committed here:
> https://svnweb.freebsd.org/changeset/base/363072
> 
> -- 
> Mateusz Guzik <mjguzik gmail.com>

Yes, thank you. This fixed the problem for me.

- Peter