Re: [linux-pm] Is it supposed to be ok to call del_gendisk whileuserspace is frozen?

From: Nigel Cunningham
Date: Fri May 14 2010 - 22:54:22 EST


Hi.

On 15/05/10 12:37, Alan Stern wrote:
On Fri, 14 May 2010, Nigel Cunningham wrote:

Hi.

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().

Why not just make it unfreezeable to start with?

If the writeback thread were unfreezable, it might wake up and try to
write dirty pages back to disks after they were already suspended.
That would not lead to good consequences...

If it syncs data as it should when we freeze processes, there won't be any problem. Perhaps this is just an argument against making syncing optional?

Regards,

Nigel
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