Date:   Thu, 9 Feb 2023 13:50:30 -0800 (PST)
From:   Hugh Dickins <hughd@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
cc:     Hugh Dickins <hughd@google.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Yang Shi <shy828301@gmail.com>,
        Zach O'Keefe <zokeefe@google.com>
Subject: Re: [PATCH 1/2] mm/MADV_COLLAPSE: set EAGAIN on unexpected page
 refcount
In-Reply-To: <20230209132846.122ad88e1c2bd0603a630e5c@linux-foundation.org>
Message-ID: <1f344fc1-834d-f1df-8a2c-79918be5b22@google.com>
References: <20230125015738.912924-1-zokeefe@google.com> <ecb2cf3-45f0-8aae-3e1-da4e79de9c27@google.com> <20230209132846.122ad88e1c2bd0603a630e5c@linux-foundation.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Thu, 9 Feb 2023, Andrew Morton wrote:
> 
> Thanks, I'll merge [1/2] into mm-hotfixes.

Great, thanks.

> 
> I'm not seeing anything in the [1/2] changelog which indicates that a
> backport is needed.  IOW,

Correct: it's just changing the errno for some racy cases from "you're
wrong, don't bother me again" to "it might be worth having another go":
not fixing an instability, as 2/2 was.

> 
> # cat .signature
> When fixing a bug, please describe the end-user visible effects of that bug.

If whatever's being run by the end-user is coded to try again on -EAGAIN,
then the end-user will less often see occasional unexplained failures.

Hugh