On 01/18/22 at 10:13pm, Jisheng Zhang wrote:
> On Sun, Jan 16, 2022 at 09:38:47PM +0800, Baoquan He wrote:
> > Hi Jisheng,
>
> Hi Baoquan,
>
> >
> > On 12/07/21 at 12:05am, Jisheng Zhang wrote:
> > > Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
> > > by a check for "IS_EN
On 12/07/21 at 02:52pm, Eric DeVolder wrote:
> This change adds members to struct kimage to facilitate crash
> hotplug support.
>
> This change also defines crash hotplug events and associated
> prototypes.
>
> Signed-off-by: Eric DeVolder
> ---
> include/linux/kexec.h | 21 +++-
On 01/19/22 at 04:23pm, Baoquan He wrote:
> On 12/07/21 at 02:52pm, Eric DeVolder wrote:
> > This change adds members to struct kimage to facilitate crash
> > hotplug support.
> >
> > This change also defines crash hotplug events and associated
> > prototypes.
> >
> > Signed-off-by: Eric DeVolder
On 01/10/22 at 02:57pm, Eric DeVolder wrote:
> This change adds members to struct kimage to facilitate crash
> hotplug support.
>
> This change also defines crash hotplug events and associated
> prototypes.
>
> Signed-off-by: Eric DeVolder
> ---
> include/linux/kexec.h | 21 +++-
Hi Baoquan,
On Wed, Jan 19, 2022 at 9:11 AM Baoquan He wrote:
>
> On 01/18/22 at 10:13pm, Jisheng Zhang wrote:
> > On Sun, Jan 16, 2022 at 09:38:47PM +0800, Baoquan He wrote:
> > > Hi Jisheng,
> >
> > Hi Baoquan,
> >
> > >
> > > On 12/07/21 at 12:05am, Jisheng Zhang wrote:
> > > > Replace the con
On 01/19/22 at 09:52am, Alexandre Ghiti wrote:
> Hi Baoquan,
>
> On Wed, Jan 19, 2022 at 9:11 AM Baoquan He wrote:
> >
> > On 01/18/22 at 10:13pm, Jisheng Zhang wrote:
> > > On Sun, Jan 16, 2022 at 09:38:47PM +0800, Baoquan He wrote:
> > > > Hi Jisheng,
> > >
> > > Hi Baoquan,
> > >
> > > >
> > >
On 01/10/22 at 02:57pm, Eric DeVolder wrote:
> For x86_64, when CPU or memory is hot un/plugged, the crash
> elfcorehdr, which describes the CPUs and memory in the system,
> must also be updated.
>
> To update the elfcorehdr for x86_64, a new elfcorehdr must be
> generated from the available CPUs
Lockdep complains that we do during mmap of the vmcore:
down_write(mmap_lock);
down_read(vmcore_cb_rwsem);
And during read of the vmcore:
down_read(vmcore_cb_rwsem);
down_read(mmap_lock);
We cannot possibly deadlock when only taking vmcore_cb_rwsem in read
mode, how
On Wed, Jan 19, 2022 at 05:33:22PM +0800, Baoquan He wrote:
> On 01/19/22 at 09:52am, Alexandre Ghiti wrote:
> > Hi Baoquan,
> >
> > On Wed, Jan 19, 2022 at 9:11 AM Baoquan He wrote:
> > >
> > > On 01/18/22 at 10:13pm, Jisheng Zhang wrote:
> > > > On Sun, Jan 16, 2022 at 09:38:47PM +0800, Baoquan
On 19/01/2022 04:13, Baoquan He wrote:
> [...]
> Thanks for the effort.
>
>
> I have some concerns about this patch, and it's still not clear to me
> why the thing done in this patch
Hi,
On Wed, Jan 19, 2022 at 12:37:02PM +0100, David Hildenbrand wrote:
> Lockdep complains that we do during mmap of the vmcore:
> down_write(mmap_lock);
> down_read(vmcore_cb_rwsem);
> And during read of the vmcore:
> down_read(vmcore_cb_rwsem);
> down_read(mmap_lock);
>
On 19.01.22 16:08, Boqun Feng wrote:
> Hi,
>
> On Wed, Jan 19, 2022 at 12:37:02PM +0100, David Hildenbrand wrote:
>> Lockdep complains that we do during mmap of the vmcore:
>> down_write(mmap_lock);
>> down_read(vmcore_cb_rwsem);
>> And during read of the vmcore:
>> down_read(vmcore
On 19.01.22 16:15, David Hildenbrand wrote:
> On 19.01.22 16:08, Boqun Feng wrote:
>> Hi,
>>
>> On Wed, Jan 19, 2022 at 12:37:02PM +0100, David Hildenbrand wrote:
>>> Lockdep complains that we do during mmap of the vmcore:
>>> down_write(mmap_lock);
>>> down_read(vmcore_cb_rwsem);
>>> And d
On Wed 2022-01-19 15:13:18, Baoquan He wrote:
> On 01/14/22 at 03:30pm, Guilherme G. Piccoli wrote:
> > The panic_print setting allows users to collect more information in a
> > panic event, like memory stats, tasks, CPUs backtraces, etc.
> > This is a pretty interesting debug mechanism, but curren
Thanks again Petr, for the deep analysis! Much appreciated.
Some comments inline below:
On 19/01/2022 12:48, Petr Mladek wrote:
>[...]
> From my POV, the function of panic notifiers is not well defined. They
> do various things, for example:
> [...]
>
> The do more that just providing informati
On Fri 2022-01-14 15:30:46, Guilherme G. Piccoli wrote:
> The panic_print setting allows users to collect more information in a
> panic event, like memory stats, tasks, CPUs backtraces, etc.
> This is a pretty interesting debug mechanism, but currently the print
> event happens *after* kmsg_dump(),
Lockdep noticed that there is chance for a deadlock if we have
concurrent mmap, concurrent read, and the addition/removal of a
callback.
As nicely explained by Boqun:
"
Lockdep warned about the above sequences because rw_semaphore is a fair
read-write lock, and the following can cause a deadlock:
Hi Petr, thanks again for the thorough review! I will implement all your
suggestions and submit a V4, all makes sense to me =)
Cheers,
Guilherme
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