[v3,01/14] memory-failure: fetch compound_head after pgmap_pfn_valid()

Commit Message

Joao Martins July 14, 2021, 7:35 p.m. UTC

memory_failure_dev_pagemap() at the moment assumes base pages (e.g.
dax_lock_page()).  For pagemap with compound pages fetch the
compound_head in case a tail page memory failure is being handled.

Currently this is a nop, but in the advent of compound pages in
dev_pagemap it allows memory_failure_dev_pagemap() to keep working.

Reported-by: Jane Chu <[e-mail]>
Signed-off-by: Joao Martins <[e-mail]>
Reviewed-by: Naoya Horiguchi <[e-mail]>
---
 mm/memory-failure.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Dan Williams July 15, 2021, 12:17 a.m. UTC | #1

On Wed, Jul 14, 2021 at 12:36 PM Joao Martins <[e-mail]> wrote:
>
> memory_failure_dev_pagemap() at the moment assumes base pages (e.g.
> dax_lock_page()).  For pagemap with compound pages fetch the
> compound_head in case a tail page memory failure is being handled.
>
> Currently this is a nop, but in the advent of compound pages in
> dev_pagemap it allows memory_failure_dev_pagemap() to keep working.
>
> Reported-by: Jane Chu <[e-mail]>
> Signed-off-by: Joao Martins <[e-mail]>
> Reviewed-by: Naoya Horiguchi <[e-mail]>

Reviewed-by: Dan Williams <[e-mail]>

Muchun Song July 15, 2021, 2:51 a.m. UTC | #2

On Thu, Jul 15, 2021 at 3:36 AM Joao Martins <[e-mail]> wrote:
>
> memory_failure_dev_pagemap() at the moment assumes base pages (e.g.
> dax_lock_page()).  For pagemap with compound pages fetch the
> compound_head in case a tail page memory failure is being handled.
>
> Currently this is a nop, but in the advent of compound pages in
> dev_pagemap it allows memory_failure_dev_pagemap() to keep working.
>
> Reported-by: Jane Chu <[e-mail]>
> Signed-off-by: Joao Martins <[e-mail]>
> Reviewed-by: Naoya Horiguchi <[e-mail]>

Reviewed-by: Muchun Song <[e-mail]>

Christoph Hellwig July 15, 2021, 6:40 a.m. UTC | #3

Can you please fix up your mailer to not mess with the subject?
That makes the thread completely unreadable.

Muchun Song July 15, 2021, 9:19 a.m. UTC | #4

On Thu, Jul 15, 2021 at 2:42 PM Christoph Hellwig <[e-mail]> wrote:
>
> Can you please fix up your mailer to not mess with the subject?
> That makes the thread completely unreadable.

Sorry. I didn't realize it before. Thanks for your reminder.

Joao Martins July 15, 2021, 1:17 p.m. UTC | #5

On 7/15/21 3:51 AM, Muchun Song wrote:
> On Thu, Jul 15, 2021 at 3:36 AM Joao Martins <[e-mail]> wrote:
>>
>> memory_failure_dev_pagemap() at the moment assumes base pages (e.g.
>> dax_lock_page()).  For pagemap with compound pages fetch the
>> compound_head in case a tail page memory failure is being handled.
>>
>> Currently this is a nop, but in the advent of compound pages in
>> dev_pagemap it allows memory_failure_dev_pagemap() to keep working.
>>
>> Reported-by: Jane Chu <[e-mail]>
>> Signed-off-by: Joao Martins <[e-mail]>
>> Reviewed-by: Naoya Horiguchi <[e-mail]>
> 
> Reviewed-by: Muchun Song <[e-mail]>
> 
Thanks!

Patch

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index eefd823deb67..c40ea28a4677 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1532,6 +1532,12 @@  static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		goto out;
 	}
 
+	/*
+	 * Pages instantiated by device-dax (not filesystem-dax)
+	 * may be compound pages.
+	 */
+	page = compound_head(page);
+
 	/*
 	 * Prevent the inode from being freed while we are interrogating
 	 * the address_space, typically this would be handled by