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SubjectRe: [PATCH] PM / Hibernate: Don't mark pages dirty when reading pages while thawing
Hi,

On Thu, 13 Jan 2011, Theodore Ts'o wrote:
> Everything was sync'ed before the hibernation, so no pages could be
> dirty. So this causes a lot of wasted I/O activity right after
> resuming from hibernation.
>
> Worse, it also causes pages from files that were opened read/only to
> be marked writeble which makes them subject to writeback. This was
> discovered when ext4 was changed to so that the jinode pointer was not
> initialized unless the file was opened read/write, and this caused
> things to blow up. But that just unmasked a problem, since the pages
> belonging to the file in question should have never been marked dirty
> in the first place. It increases the chances the text blocks for
> executables like /usr/bin/killall will get corrupted when they are
> needlessly written, and of course it means extra write cycles to the
> SSD.
>
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
> Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
> Cc: linux-pm@lists.linux-foundation.org
> ---
> kernel/power/block_io.c | 2 --
> 1 files changed, 0 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/power/block_io.c b/kernel/power/block_io.c
> index 83bbc7c..108a4f3 100644
> --- a/kernel/power/block_io.c
> +++ b/kernel/power/block_io.c
> @@ -49,8 +49,6 @@ static int submit(int rw, struct block_device *bdev, sector_t sector,
> if (bio_chain == NULL) {
> submit_bio(bio_rw, bio);
> wait_on_page_locked(page);
> - if (rw == READ)
> - bio_set_pages_dirty(bio);
> bio_put(bio);
> } else {
> if (rw == READ)
> --
> 1.7.3.1
>
>

I did some test with this patch applied, but sadly it didn't help.
The testcase was reduced to one hibernation followed by a sync.

Regards,
Sebastian


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