On 4/24/21 1:12 AM, Dan Williams wrote:
On Thu, Mar 25, 2021 at 4:10 PM Joao Martins
> 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 we are handling a tail page memory failure.
> 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 <jane.chu(a)oracle.com>
> Signed-off-by: Joao Martins <joao.m.martins(a)oracle.com>
> mm/memory-failure.c | 2 ++
> 1 file changed, 2 insertions(+)
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 24210c9bd843..94240d772623 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1318,6 +1318,8 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int
> goto out;
> + page = compound_head(page);
Unless / until we do compound pages for the filesystem-dax case, I
would add a comment like:
/* pages instantiated by device-dax (not filesystem-dax) may be
compound pages */
I've fixed up with the comment.