From: Vlastimil Babka <vbabka@suse.cz>
To: Matthew Wilcox <willy@infradead.org>, yangshiguang1011@163.com
Cc: harry.yoo@oracle.com, akpm@linux-foundation.org, cl@gentwo.org,
rientjes@google.com, roman.gushchin@linux.dev, glittao@gmail.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
yangshiguang <yangshiguang@xiaomi.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v3] mm: slub: avoid wake up kswapd in set_track_prepare
Date: Mon, 25 Aug 2025 17:42:52 +0200 [thread overview]
Message-ID: <54d9e5ac-5a51-4901-9b13-4c248aada2d7@suse.cz> (raw)
In-Reply-To: <aKxZp_GgYVzp8Uvt@casper.infradead.org>
On 8/25/25 14:40, Matthew Wilcox wrote:
> On Mon, Aug 25, 2025 at 08:17:37PM +0800, yangshiguang1011@163.com wrote:
>> Avoid deadlock caused by implicitly waking up kswapd by
>> passing in allocation flags.
> [...]
>> + /* Preemption is disabled in ___slab_alloc() */
>> + gfp_flags &= ~(__GFP_DIRECT_RECLAIM);
>
> If you don't mean __GFP_KSWAPD_RECLAIM here, the explanation needs to
> be better.
It was suggested by Harry here:
https://lore.kernel.org/all/aKKhUoUkRNDkFYYb@harry/
I think the comment is enough? Disabling preemption means we can't direct
reclaim, but we can wake up kswapd. If the slab caller context is such that
we can't, __GFP_KSWAPD_RECLAIM already won't be in the gfp_flags.
But I think we should mask our also __GFP_NOFAIL and add __GFP_NOWARN?
(we should get some common helpers for these kinds of gfp flag manipulations
already)
next prev parent reply other threads:[~2025-08-25 15:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-25 12:17 yangshiguang1011
2025-08-25 12:40 ` Matthew Wilcox
2025-08-25 15:42 ` Vlastimil Babka [this message]
2025-08-27 5:17 ` Harry Yoo
2025-08-27 7:45 ` yangshiguang
2025-08-27 8:40 ` Vlastimil Babka
2025-08-29 11:29 ` yangshiguang
2025-08-29 13:08 ` Vlastimil Babka
2025-08-30 1:48 ` yangshiguang
2025-08-27 8:00 ` Vlastimil Babka
2025-08-27 8:44 ` Vlastimil Babka
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