Re: + mm-vmscan-fix-a-bug-calling-wakeup_kswapd-with-a-wrong-zone-index.patch added to mm-hotfixes-unstable branch

[Oscar Salvador <osalvador@suse.de>]

On Mon, Feb 19, 2024 at 07:25:38PM -0800, Andrew Morton wrote:
> From: Byungchul Park <byungchul@sk.com>
> Subject: mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index
> Date: Fri, 16 Feb 2024 20:15:02 +0900
> 
> With numa balancing on, when a numa system is running where a numa node
> doesn't have its local memory so it has no managed zones, the following
> oops has been observed.  It's because wakeup_kswapd() is called with a
> wrong zone index, -1.  Fixed it by checking the index before calling
> wakeup_kswapd().
...
...

> 
> Link: https://lkml.kernel.org/r/20240216111502.79759-1-byungchul@sk.com
> Signed-off-by: Byungchul Park <byungchul@sk.com>
> Reported-by: Hyeongtak Ji <hyeongtak.ji@sk.com>
> Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: "Huang, Ying" <ying.huang@intel.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

It's a shame that N_MEMORY can actually have no memory (e.g: memmap
consuming all zone's memory), but here we are:

Reviewed-by: Oscar Salvador <osalvador@suse.de>


-- 
Oscar Salvador
SUSE Labs