linux-kernel - Re: [PATCH 3/4] mm: vrealloc: properly document __GFP

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Message-ID: <4908d9a3-8b04-4808-8190-c1b602cba9dd@suse.cz>
Date: Wed, 31 Jul 2024 16:43:39 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Danilo Krummrich <dakr@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: urezki@...il.com, hch@...radead.org, mhocko@...e.com,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 3/4] mm: vrealloc: properly document __GFP_ZERO behavior

On 7/31/24 12:43 AM, Danilo Krummrich wrote:
> On Tue, Jul 30, 2024 at 02:19:53PM -0700, Andrew Morton wrote:
>> On Tue, 30 Jul 2024 20:49:43 +0200 Danilo Krummrich <dakr@...nel.org> wrote:
>> 
>> > Properly document that if __GFP_ZERO logic is requested, callers must
>> > ensure that, starting with the initial memory allocation, every
>> > subsequent call to this API for the same memory allocation is flagged
>> > with __GFP_ZERO. Otherwise, it is possible that __GFP_ZERO is not fully
>> > honored by this API.
>> 
>> I appear to have just seen this, in a separate mailing.
> 
> What you have seen in a separate mail is a similar patch for krealloc() [1].
> This one is a fixup for vrealloc() from a previous submission you've applied to
> mm-unstable.
> 
>> 
>> Please, slow down.  We have two months.  Await reviewer feedback, spend
>> time over those changelogs, value clarity and accuracy and completeness
>> over hastiness.  The only reason for rushing things is if a patch is
>> disrupting ongoing testing of the linux-next tree.
> 
> There was a discussion in [2], which lead to this fixup series.
> 
> In terms of changelogs this series is indeed a bit "lax", since I have
> recognized that you queue up fixup patches for changes that did already land in
> mm-unstable to be squashed into the original commits later on.

Some of the changes in the fixups would however ideally result in udpdates
to the original changelogs in addition to squashing code. Also with 4 fixups
to 2 original patches it might be IMHO better to squash on your side and
resend as a full replacement. Perhaps also together with the other 2 patches
about __GFP_ZERO for krealloc in a single series. As Andrew mentioned we are
early in the rc phase to afford this.

> [1] https://lore.kernel.org/linux-mm/20240730194214.31483-1-dakr@kernel.org/
> [2] https://lore.kernel.org/linux-mm/20240722163111.4766-1-dakr@kernel.org/T/#m065a7f875b44dc945dd535c2b7168c3d77a98993