From: Gaash Hazan <gaashh@yahoo•com>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev@ozlabs•org, Paul Mackerras <paulus@samba•org>,
gaash-ppclnx@gaashh•com, Gilad Ben-Yossef <gilad@codefidence•com>
Subject: Re: [PATCH] powerpc: Fix deadlock with mmu_hash_lock in hash_page_sync
Date: Mon, 31 Mar 2008 01:30:37 -0700 (PDT) [thread overview]
Message-ID: <31342.74174.qm@web39604.mail.mud.yahoo.com> (raw)
In-Reply-To: <8C22373EA650AF40928EEA0C188D62D206C71041@xmb-ams-338.emea.cisco.com>
> -----Original Message-----
> From: Benjamin Herrenschmidt
> [mailto:benh@kernel•crashing.org]
> Sent: Monday, March 31, 2008 0:49
> To: gaash-ppclnx@gaashh•com
> Cc: linuxppc-dev@ozlabs•org; Gilad Ben-Yossef; Paul
> Mackerras
> Subject: [PATCH] powerpc: Fix deadlock with
> mmu_hash_lock in
> hash_page_sync
>
> hash_page_sync() takes and releases the low level
> mmu hash lock in order
> to sync with other processors disposing of page
> tables. Because that
> lock can be needed to service hash misses triggered
> by interrupt
> handler, taking it must be done with interrupts off.
> However,
> hash_page_sync() appear to be called with interrupts
> enabled, thus
> causing occasional deadlocks.
>
> We fix it by making sure hash_page_sync() masks
> interrupts while holding
> the lock.
>
> Signed-off-by: Benjamin Herrenschmidt
> <benh@kernel•crashing.org>
> ---
>
> Please test and report asap thought it's probably
> too late for 2.6.25,
> it can still go into stable later on.
>
Thank you for the quick acknowledgment and patch.
Patch works well.
Thanks,
Gaash
next parent reply other threads:[~2008-03-31 8:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <8C22373EA650AF40928EEA0C188D62D206C71041@xmb-ams-338.emea.cisco.com>
2008-03-31 8:30 ` Gaash Hazan [this message]
2008-03-30 21:28 mmu_hash_lock deadlock causes kernel stuck at 2.6.21 SMP powerpc 32bit Gaash Hazan
2008-03-30 21:49 ` [PATCH] powerpc: Fix deadlock with mmu_hash_lock in hash_page_sync Benjamin Herrenschmidt
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