LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Wang Qing <wangqing@vivo.com>,
	Santosh Sivaraj <santosh@fossix.org>,
	Sumit Garg <sumit.garg@linaro.org>, Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 2/5] kernel/watchdog_hld: clarify the condition in hardlockup_detector_event_create()
Date: Wed, 15 Sep 2021 15:45:06 +0200	[thread overview]
Message-ID: <YUH44qrky9oM+3nU@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210915035103.15586-3-kernelfans@gmail.com>

On Wed, Sep 15, 2021 at 11:51:00AM +0800, Pingfan Liu wrote:
> hardlockup_detector_event_create() indirectly calls
> kmem_cache_alloc_node(), which is blockable.
> 
> So here, the really planned context is is_percpu_thread().
> 
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Wang Qing <wangqing@vivo.com>
> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
> Cc: Santosh Sivaraj <santosh@fossix.org>
> Cc: Sumit Garg <sumit.garg@linaro.org>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> To: linux-kernel@vger.kernel.org
> ---
>  kernel/watchdog_hld.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
> index 247bf0b1582c..6876e796dbf5 100644
> --- a/kernel/watchdog_hld.c
> +++ b/kernel/watchdog_hld.c
> @@ -165,10 +165,13 @@ static void watchdog_overflow_callback(struct perf_event *event,
>  
>  static int hardlockup_detector_event_create(void)
>  {
> -	unsigned int cpu = smp_processor_id();
> +	unsigned int cpu;
>  	struct perf_event_attr *wd_attr;
>  	struct perf_event *evt;
>  
> +	/* This function plans to execute in cpu bound kthread */
> +	BUG_ON(!is_percpu_thread());
> +	cpu = raw_smp_processor_id();
>  	wd_attr = &wd_hw_attr;
>  	wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);

This patch makes no sense.

  parent reply	other threads:[~2021-09-15 13:46 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-15  3:50 [PATCH 0/5] watchdog_hld cleanup and async model for arm64 Pingfan Liu
2021-09-15  3:50 ` [PATCH 1/5] kernel/watchdog: remove useless WATCHDOG_DEFAULT Pingfan Liu
2021-09-15  3:51 ` [PATCH 2/5] kernel/watchdog_hld: clarify the condition in hardlockup_detector_event_create() Pingfan Liu
2021-09-15  4:06   ` Andrew Morton
2021-09-16  3:47     ` Pingfan Liu
2021-09-15 13:45   ` Peter Zijlstra [this message]
2021-09-16  3:57     ` Pingfan Liu
2021-09-16  8:02       ` Petr Mladek
2021-09-17 15:08         ` Pingfan Liu
2021-09-15  3:51 ` [PATCH 3/5] kernel/watchdog: adapt the watchdog_hld interface for async model Pingfan Liu
2021-09-15 14:02   ` Peter Zijlstra
2021-09-16  3:07     ` Pingfan Liu
2021-09-16  8:29   ` Petr Mladek
2021-09-16  8:36     ` Petr Mladek
2021-09-17 15:41       ` Pingfan Liu
2021-09-20  8:20         ` Petr Mladek
2021-09-22  4:26           ` Pingfan Liu
2021-09-17 14:43     ` Pingfan Liu
2021-09-15  3:51 ` [PATCH 4/5] kernel/watchdog_hld: simplify the detecting of hld watchdog Pingfan Liu
2021-09-15  3:51 ` [PATCH 5/5] arm64/watchdog_hld: enable hard lockup on arm64 platform Pingfan Liu
2021-09-17 15:11   ` Pingfan Liu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YUH44qrky9oM+3nU@hirez.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=akpm@linux-foundation.org \
    --cc=kernelfans@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=pmladek@suse.com \
    --cc=santosh@fossix.org \
    --cc=sumit.garg@linaro.org \
    --cc=wangqing@vivo.com \
    --cc=will@kernel.org \
    --subject='Re: [PATCH 2/5] kernel/watchdog_hld: clarify the condition in hardlockup_detector_event_create()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).