Re: [PATCH] mm: check the return value of lookup_page_ext for all call sites

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Nov 24, 2017 at 10:30:32AM +0100, Michal Hocko wrote:
> From: Yang Shi <yang.shi@linaro.org>
> 
> commit f86e4271978bd93db466d6a95dad4b0fdcdb04f6 upstream.
> 
> Per the discussion with Joonsoo Kim [1], we need check the return value
> of lookup_page_ext() for all call sites since it might return NULL in
> some cases, although it is unlikely, i.e.  memory hotplug.
> 
> Tested with ltp with "page_owner=0".
> 
> [1] http://lkml.kernel.org/r/20160519002809.GA10245@js1304-P5Q-DELUXE
> 
> [akpm@linux-foundation.org: fix build-breaking typos]
> [arnd@arndb.de: fix build problems from lookup_page_ext]
>   Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel
> [akpm@linux-foundation.org: coding-style fixes]
> Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@linaro.org
> Signed-off-by: Yang Shi <yang.shi@linaro.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Can you send a patch on top of 4.4.101 to resolve this instead?

thanks,

greg k-h