linux-kernel - Re: [linux-pm] Is it supposed to be ok to call del

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Message-ID: <AANLkTimBxoCCeT_ns30JTIGKqgkiRIvKTf4LfE3mopkS@mail.gmail.com>
Date:	Thu, 13 May 2010 15:20:07 -0700
From:	Matt Reimer <mattjreimer@...il.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	Maxim Levitsky <maximlevitsky@...il.com>,
	linux-pm <linux-pm@...ts.linux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>
Subject: Re: [linux-pm] Is it supposed to be ok to call del_gendisk while 
	userspace is frozen?

On Thu, May 13, 2010 at 2:54 PM, Alan Stern <stern@...land.harvard.edu> wrote:
> On Thu, 13 May 2010, Matt Reimer wrote:
>
>> So how does the attached patch look?
>>
>> Matt
>>
>>
>> From 20d8340471eb05aa54af1349f4ddccecd9c230c6 Mon Sep 17 00:00:00 2001
>> From: Matt Reimer <mreimer@...systems.com>
>> Date: Thu, 13 May 2010 14:36:54 -0700
>> Subject: [PATCH] fs: prevent hang on suspend/resume when MMC/SD card present
>>
>> Devices can come and go from the MMC/SD bus during suspend or resume,
>> when the writeback thread is frozen, resulting in a hang. So thaw the
>> writeback thread in del_gendisk() to prevent the hang.
>
> I don't see anything wrong with the patch itself, but I dislike the
> description.  Devices can come and go from any hotpluggable bus, not
> just MMC/SD.  That just happens to be the first place the problem was
> observed.

Good point. How about this?

Matt

>From 813bd223e5a2fa577b9e64ddf12654a93d0aab8b Mon Sep 17 00:00:00 2001
From: Matt Reimer <mreimer@...systems.com>
Date: Thu, 13 May 2010 14:36:54 -0700
Subject: [PATCH] fs: prevent hang on suspend/resume when MMC/SD card present

Devices can come and go bus during suspend or resume, when the
writeback thread is frozen, resulting in a hang. Prevent the hang
by thawing the writeback thread in del_gendisk().

Signed-off-by: Matt Reimer <mreimer@...systems.com>
---
 fs/partitions/check.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index e238ab2..b303919 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -666,6 +666,8 @@ void del_gendisk(struct gendisk *disk)
        struct disk_part_iter piter;
        struct hd_struct *part;

+       thaw_process(disk->queue->backing_dev_info.wb.task);
+
        /* invalidate stuff */
        disk_part_iter_init(&piter, disk,
                             DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
-- 
1.7.0.4

Download attachment "0001-fs-prevent-hang-on-suspend-resume-when-MMC-SD-card-p.patch" of type "application/octet-stream" (998 bytes)