linux-kernel - Re: [PATCH 06/10] mm: update coredump logic to correctly use bitmap mm flags

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Message-ID: <9ea82e7a-9eea-4bb5-b57a-f5c4714bc732@lucifer.local>
Date: Fri, 15 Aug 2025 15:12:02 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Christian Brauner <brauner@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
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Subject: Re: [PATCH 06/10] mm: update coredump logic to correctly use bitmap
 mm flags

On Fri, Aug 15, 2025 at 03:52:38PM +0200, Christian Brauner wrote:
> On Tue, Aug 12, 2025 at 04:44:15PM +0100, Lorenzo Stoakes wrote:
> > The coredump logic is slightly different from other users in that it both
> > stores mm flags and additionally sets and gets using masks.
> >
> > Since the MMF_DUMPABLE_* flags must remain as they are for uABI reasons,
> > and of course these are within the first 32-bits of the flags, it is
> > reasonable to provide access to these in the same fashion so this logic can
> > all still keep working as it has been.
> >
> > Therefore, introduce coredump-specific helpers __mm_flags_get_dumpable()
> > and __mm_flags_set_mask_dumpable() for this purpose, and update all core
>
> Why the double underscore here? Just looks a bit ugly so if we can avoid
> it I would but if not:
>
> Reviewed-by: Christian Brauner <brauner@...nel.org>

Thanks!

The double underscore is to fit the bitops convention of bitop() is atomic,
__bitop() is non-atomic. Obviously these operations were and are non-atomic
so this is where this came from.

I do that because the vast majority of operations on mm flags were atomic
bitops before so it is in keeping with.