Re: [PATCH 4.19 000/338] 4.19.238-rc1 review

[Trond Myklebust <trondmy@hammerspace.com>]

> On Dec 16, 2022, at 13:31, Michael Trimarchi <michael@amarulasolutions.com> wrote:
> 
> [You don't often get email from michael@amarulasolutions.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> Hi Neil
> 
> On Tue, Apr 26, 2022 at 12:29:55PM +1000, NeilBrown wrote:
>> On Thu, 21 Apr 2022, Naresh Kamboju wrote:
>>> On Mon, 18 Apr 2022 at 14:09, Naresh Kamboju <naresh.kamboju@linaro.org> wrote:
>>>> 
>>>> On Thu, 14 Apr 2022 at 18:45, Greg Kroah-Hartman
>>>> <gregkh@linuxfoundation.org> wrote:
>>>>> 
>>>>> This is the start of the stable review cycle for the 4.19.238 release.
>>>>> There are 338 patches in this series, all will be posted as a response
>>>>> to this one.  If anyone has any issues with these being applied, please
>>>>> let me know.
>>>>> 
>>>>> Responses should be made by Sat, 16 Apr 2022 11:07:54 +0000.
>>>>> Anything received after that time might be too late.
>>>>> 
>>>>> The whole patch series can be found in one patch at:
>>>>>        https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.238-rc1.gz
>>>>> or in the git tree and branch at:
>>>>>        git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
>>>>> and the diffstat can be found below.
>>>>> 
>>>>> thanks,
>>>>> 
>>>>> greg k-h
>>>> 
>>>> 
>>>> Following kernel warning noticed on arm64 Juno-r2 while booting
>>>> stable-rc 4.19.238. Here is the full test log link [1].
>>>> 
>>>> [    0.000000] Booting Linux on physical CPU 0x0000000100 [0x410fd033]
>>>> [    0.000000] Linux version 4.19.238 (tuxmake@tuxmake) (gcc version
>>>> 11.2.0 (Debian 11.2.0-18)) #1 SMP PREEMPT @1650206156
>>>> [    0.000000] Machine model: ARM Juno development board (r2)
>>>> <trim>
>>>> [   18.499895] ================================
>>>> [   18.504172] WARNING: inconsistent lock state
>>>> [   18.508451] 4.19.238 #1 Not tainted
>>>> [   18.511944] --------------------------------
>>>> [   18.516222] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
>>>> [   18.522242] kworker/u12:3/60 [HC0[0]:SC0[0]:HE1:SE1] takes:
>>>> [   18.527826] (____ptrval____)
>>>> (&(&xprt->transport_lock)->rlock){+.?.}, at: xprt_destroy+0x70/0xe0
>>>> [   18.536648] {IN-SOFTIRQ-W} state was registered at:
>>>> [   18.541543]   lock_acquire+0xc8/0x23c
>> 
>> Prior to Linux 5.3, ->transport_lock needs spin_lock_bh() and
>> spin_unlock_bh().
>> 
> 
> We get the same deadlock or similar one and we think that
> can be connected to this thread on 4.19.243. For us is a bit
> difficult to hit but we are going to apply this change
> 
> net: sunrpc: Fix deadlock in xprt_destroy
> 
> Prior to Linux 5.3, ->transport_lock needs spin_lock_bh() and
> spin_unlock_bh().
> 
> Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
> ---
> net/sunrpc/xprt.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index d05fa7c36d00..b1abf4848bbc 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -1550,9 +1550,9 @@ static void xprt_destroy(struct rpc_xprt *xprt)
>         * is cleared.  We use ->transport_lock to ensure the mod_timer()
>         * can only run *before* del_time_sync(), never after.
>         */
> -       spin_lock(&xprt->transport_lock);
> +       spin_lock_bh(&xprt->transport_lock);
>        del_timer_sync(&xprt->timer);
> -       spin_unlock(&xprt->transport_lock);
> +       spin_unlock_bh(&xprt->transport_lock);
> 
>        /*
>         * Destroy sockets etc from the system workqueue so they can
> —

Agreed. When backporting to kernels that are older than 5.3.x, the transport lock needs to be taken using the bh-safe spin lock variants.

Reviewed-by: Trond Myklebust <trond.myklebust@hammerspace.com <mailto:trond.myklebust@hammerspace.com>>

_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com