Re: [RFC PATCH] panic: fix deadlock in panic()

2020-06-05 Thread Petr Mladek
On Fri 2020-06-05 18:42:57, chengjian (D) wrote: > Hi, Petr > > On 2020/6/4 16:29, Petr Mladek wrote: > > > It might cause double unlock (deadlock) on architectures that did not > > use NMI to stop the CPUs. > > > > I have created a conservative fix for this problem for SLES, see > > https://git

Re: [RFC PATCH] panic: fix deadlock in panic()

2020-06-05 Thread chengjian (D)
Hi, Petr On 2020/6/4 16:29, Petr Mladek wrote: It might cause double unlock (deadlock) on architectures that did not use NMI to stop the CPUs. I have created a conservative fix for this problem for SLES, see https://github.com/openSUSE/kernel-source/blob/SLE15-SP2-UPDATE/patches.suse/printk-pa

Re: [RFC PATCH] panic: fix deadlock in panic()

2020-06-04 Thread Petr Mladek
On Wed 2020-06-03 14:19:15, Cheng Jian wrote: > A deadlock caused by logbuf_lock occurs when panic: > > a) Panic CPU is running in non-NMI context > b) Panic CPU sends out shutdown IPI via NMI vector > c) One of the CPUs that we bring down via NMI vector holded logbuf_lock >

Re: [RFC PATCH] panic: fix deadlock in panic()

2020-06-04 Thread Sergey Senozhatsky
On (20/06/03 14:19), Cheng Jian wrote: > A deadlock caused by logbuf_lock occurs when panic: > > a) Panic CPU is running in non-NMI context > b) Panic CPU sends out shutdown IPI via NMI vector > c) One of the CPUs that we bring down via NMI vector holded logbuf_lock > d) P

[RFC PATCH] panic: fix deadlock in panic()

2020-06-03 Thread Cheng Jian
A deadlock caused by logbuf_lock occurs when panic: a) Panic CPU is running in non-NMI context b) Panic CPU sends out shutdown IPI via NMI vector c) One of the CPUs that we bring down via NMI vector holded logbuf_lock d) Panic CPU try to hold logbuf_lock, then dead