svn commit: r363069 - head/sys/kern

[Mateusz Guzik]

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>