Re: [PATCH] ubifs: Get/put page when changing PG_private

[Richard Weinberger]

Am Montag, 17. Dezember 2018, 11:59:44 CET schrieb Kirill A. Shutemov:
> On Sat, Dec 15, 2018 at 04:01:30PM +0100, Richard Weinberger wrote:
> > The page migration code assumes that a page with PG_private
> > set has its page count elevated by 1.
> > UBIFS never did this and therefore the migration code was unable
> > to migrate some pages owned by UBIFS.
> > The lead to situations where the CMA memory allocator failed to
> > allocate memory.
> > 
> > Fix this by using get/put_page when changing PG_private.
> 
> Looks good to me.
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> 
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Cc: zhangjun <openzhangj@xxxxxxxxx>
> > Fixes: 4ac1c17b2044 ("UBIFS: Implement ->migratepage()")
> 
> It is fair to reference the commit here. But I believe the bug itself
> predates the commit and relevant not only for migration.

My intention was not blaming you. :)
IMHO backporting the fix makes only sense up to that commit.
 
> We might make it clear in the commit message.

Fair point, I'll rephrase.

Thanks,
//richard