From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Oliver O'Halloran <oohall@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: Sam Bobroff <sbobroff@linux.ibm.com>,
Oliver O'Halloran <oohall@gmail.com>
Subject: Re: [PATCH] powerpc/eeh: Only dump stack once if an MMIO loop is detected
Date: Wed, 29 Jan 2020 16:17:22 +1100 (AEDT) [thread overview]
Message-ID: <486sDf2z6sz9s1x@ozlabs.org> (raw)
In-Reply-To: <20191016012536.22588-1-oohall@gmail.com>
On Wed, 2019-10-16 at 01:25:36 UTC, Oliver O'Halloran wrote:
> Many drivers don't check for errors when they get a 0xFFs response from an
> MMIO load. As a result after an EEH event occurs a driver can get stuck in
> a polling loop unless it some kind of internal timeout logic.
>
> Currently EEH tries to detect and report stuck drivers by dumping a stack
> trace after eeh_dev_check_failure() is called EEH_MAX_FAILS times on an
> already frozen PE. The value of EEH_MAX_FAILS was chosen so that a dump
> would occur every few seconds if the driver was spinning in a loop. This
> results in a lot of spurious stack traces in the kernel log.
>
> Fix this by limiting it to printing one stack trace for each PE freeze. If
> the driver is truely stuck the kernel's hung task detector is better suited
> to reporting the probelm anyway.
>
> Cc: Sam Bobroff <sbobroff@linux.ibm.com>
> Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/4e0942c0302b5ad76b228b1a7b8c09f658a1d58a
cheers
prev parent reply other threads:[~2020-01-29 5:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 1:25 [PATCH] powerpc/eeh: Only dump stack once if an MMIO loop is detected Oliver O'Halloran
2019-10-16 3:44 ` Sam Bobroff
2020-01-29 5:17 ` Michael Ellerman [this message]
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