From: Chris Ball <cjb@laptop.org>
To: Will Deacon <will.deacon@arm.com>
Cc: linux-mmc@vger.kernel.org, Pierre Ossman <drzeus@drzeus.cx>
Subject: Re: [PATCH] mmc: mmci: reduce max_blk_count to avoid overflowing max_req_size
Date: Fri, 02 Mar 2012 16:02:38 -0500 [thread overview]
Message-ID: <m2ehtan2c1.fsf@bob.laptop.org> (raw)
In-Reply-To: <1330082721-6021-1-git-send-email-will.deacon@arm.com> (Will Deacon's message of "Fri, 24 Feb 2012 11:25:21 +0000")
Hi Will,
On Fri, Feb 24 2012, Will Deacon wrote:
> On a system with large pages (64k in my case), the following BUG is
> triggered in MMC core:
>
> [ 2.338023] BUG: failure at drivers/mmc/core/core.c:221/mmc_start_request()!
> [ 2.338102] Kernel panic - not syncing: BUG!
> [ 2.338155] Call trace:
> [ 2.338228] [<ffffffc00008635c>] dump_backtrace+0x0/0x120
> [ 2.338317] [<ffffffc0003365ec>] dump_stack+0x14/0x1c
> [ 2.338403] [<ffffffc000336990>] panic+0xbc/0x1f0
> [ 2.338498] [<ffffffc00027a494>] mmc_start_request+0x154/0x184
> [ 2.338600] [<ffffffc00027abdc>] mmc_start_req+0x110/0x140
> [ 2.338701] [<ffffffc00028604c>] mmc_blk_issue_rw_rq+0x7c/0x39c
> [ 2.338804] [<ffffffc00028652c>] mmc_blk_issue_rq+0x1c0/0x468
> [ 2.338905] [<ffffffc000287564>] mmc_queue_thread+0x68/0x118
> [ 2.338995] [<ffffffc0000bc308>] kthread+0x84/0x8c
>
> This is because of a 64k request with a max_req_size of 64k-1 bytes.
>
> The following patch fixes the problem by limiting the max_blk_count
> such that max_blk_count * max_blk_size == max_req_size. I couldn't
> pursuade the compiler to emit a shift instead of a div without encoding
> the shift explicitly.
>
> Cc: Pierre Ossman <drzeus@drzeus.cx>
> Cc: Chris Ball <cjb@laptop.org>
> Signed-off-by: Will Deacon <will.deacon@arm.com>
Thanks, pushed to mmc-next for 3.3.
- Chris.
--
Chris Ball <cjb@laptop.org> <http://printf.net/>
One Laptop Per Child
prev parent reply other threads:[~2012-03-02 21:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-24 11:25 [PATCH] mmc: mmci: reduce max_blk_count to avoid overflowing max_req_size Will Deacon
2012-02-29 18:41 ` Will Deacon
2012-03-02 21:02 ` Chris Ball [this message]
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