linux-kernel - Re: [PATCH v3 1/2] mm: memcg/slab: Properly set up gfp flags for objcg pointer array

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Date:   Wed, 5 May 2021 09:46:39 -0700
From:   Roman Gushchin <guro@...com>
To:     Waiman Long <longman@...hat.com>
CC:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Shakeel Butt <shakeelb@...gle.com>,
        <linux-kernel@...r.kernel.org>, <cgroups@...r.kernel.org>,
        <linux-mm@...ck.org>
Subject: Re: [PATCH v3 1/2] mm: memcg/slab: Properly set up gfp flags for
 objcg pointer array

On Wed, May 05, 2021 at 11:46:12AM -0400, Waiman Long wrote:
> Since the merging of the new slab memory controller in v5.9, the page
> structure may store a pointer to obj_cgroup pointer array for slab pages.
> Currently, only the __GFP_ACCOUNT bit is masked off. However, the array
> is not readily reclaimable and doesn't need to come from the DMA buffer.
> So those GFP bits should be masked off as well.
> 
> Do the flag bit clearing at memcg_alloc_page_obj_cgroups() to make sure
> that it is consistently applied no matter where it is called.
> 
> Fixes: 286e04b8ed7a ("mm: memcg/slab: allocate obj_cgroups for non-root slab pages")
> Signed-off-by: Waiman Long <longman@...hat.com>
> ---
>  mm/memcontrol.c | 8 ++++++++
>  mm/slab.h       | 1 -
>  2 files changed, 8 insertions(+), 1 deletion(-)

Acked-by: Roman Gushchin <guro@...com>

Thanks!