Re: [PATCH v3] mm/memcontrol: fix reclaim_options leak in try_charge_memcg()

[Johannes Weiner <hannes@cmpxchg.org>]

On Wed, Mar 18, 2026 at 10:19:46PM +0000, Bing Jiao wrote:
> In try_charge_memcg(), the 'reclaim_options' variable is initialized
> once at the start of the function. However, the function contains a
> retry loop. If reclaim_options were modified during an iteration
> (e.g., by encountering a memsw limit), the modified state would
> persist into subsequent retries.
> 
> This leads to incorrect reclaim behavior. Specifically,
> MEMCG_RECLAIM_MAY_SWAP is cleared when the combined memcg->memsw limit
> is reached. After reclaimation attemps, a subsequent retry may
> successfully charge memcg->memsw but fail on the memcg->memory charge.
> In this case, swapping should be permitted, but the carried-over state
> prevents it.
> 
> Fix by moving the initialization of 'reclaim_options' inside the
> retry loop, ensuring a clean state for every reclaim attempt.
> 
> Fixes: 6539cc053869 ("mm: memcontrol: fold mem_cgroup_do_charge()")
> Signed-off-by: Bing Jiao <bingjiao@google.com>
> Reviewed-by: Yosry Ahmed <yosry@kernel.org>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>