From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: "Barry Song (Xiaomi)" <baohua@kernel.org>
Cc: senozhatsky@chromium.org, akpm@linux-foundation.org,
bigeasy@linutronix.de, hdanton@sina.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
minchan@kernel.org, ryncsn@gmail.com, yosry.ahmed@linux.dev,
surenb@google.com, Dongdong Zhang <zhangdongdong5@xiaomi.com>
Subject: Re: [RFC PATCH] zram: avoid preemption with CPU-based compression backends
Date: Wed, 5 Aug 2026 10:27:01 +0900 [thread overview]
Message-ID: <anKQ_qZ1-Q6FchZ9@google.com> (raw)
In-Reply-To: <20260805005545.66112-1-baohua@kernel.org>
On (26/08/05 08:55), Barry Song (Xiaomi) wrote:
> Since commit 2efa9e9eb4db ("zram: permit preemption with active
> compression stream"), a major Android regression has been reported.
>
> The reason is that compression/decompression is now sleepable and
> preemptible. This means a stream may be migrated to another CPU or
> be preempted while holding the stream mutex. As a result, high
> priority UI threads may get stuck waiting for the mutex during swap-in.
[..]
> We add an async flag (currently false for almost all backends) to
> indicate whether a backend is asynchronous. For synchronous
> backends, we use preempt_disable() in the !PREEMPT_RT case. A
I wonder what does that report say. Is that what I think it is
(we discussed something RT related privately recently)?
next prev parent reply other threads:[~2026-08-05 1:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-05 0:55 [RFC PATCH] zram: avoid preemption with CPU-based compression backends Barry Song (Xiaomi)
2026-08-05 1:27 ` Sergey Senozhatsky [this message]
2026-08-05 1:57 ` Barry Song
2026-08-05 2:09 ` Sergey Senozhatsky
2026-08-05 5:09 ` Barry Song
2026-08-05 5:21 ` Sergey Senozhatsky
2026-08-05 7:50 ` Barry Song
2026-08-05 8:46 ` Sergey Senozhatsky
2026-08-05 9:01 ` Sergey Senozhatsky
2026-08-05 10:07 ` Barry Song (Xiaomi)
2026-08-05 10:25 ` Sergey Senozhatsky
2026-08-05 10:34 ` Barry Song
2026-08-05 10:37 ` Sergey Senozhatsky
2026-08-05 2:19 ` Bo Zhang
2026-08-05 2:31 ` Barry Song
2026-08-05 7:30 ` Sergey Senozhatsky
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