From: Christoph Hellwig <hch@infradead.org>
To: Yousef Alhouseen <alhouseenyousef@gmail.com>
Cc: djwong@kernel.org, cem@kernel.org, linux-xfs@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] xfs: zero newly allocated btree root space
Date: Wed, 1 Jul 2026 03:56:17 -0700 [thread overview]
Message-ID: <akTyUXMN4_I1fOaM@infradead.org> (raw)
In-Reply-To: <CAMuQ4bXGcSf2=MVknbgt709Jkv4fgiCx9UEocSEFTDkzPY5bFg@mail.gmail.com>
On Tue, Jun 30, 2026 at 01:39:35PM -0700, Yousef Alhouseen wrote:
> Yes. The KMSAN report traces the allocation through
> xfs_bmap_extents_to_btree(), which calls xfs_bmap_broot_realloc(...,
> 1). With no existing root, that reaches krealloc(NULL, new_size). The
> conversion initializes the block header, first key, and end-anchored
> pointer, but does not initialize the layout/alignment gap within the
> full if_broot_bytes allocation. XFS_ILOG_DBROOT later copies that
> complete byte count into the log.
>
> So the observed bytes are root-layout slack from the extents-to-btree
> conversion, rather than record storage that a later insertion should
> have filled.
This almost sounds like we should explicitly zero this case just for that
particular case. Although Darrick was kinda heading in a different
direction and I don't want to start a fight here.
next prev parent reply other threads:[~2026-07-01 10:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-30 10:06 [PATCH v2] xfs: zero newly allocated btree root space Yousef Alhouseen
2026-06-30 16:11 ` Darrick J. Wong
2026-06-30 20:39 ` Yousef Alhouseen
2026-07-01 10:56 ` Christoph Hellwig [this message]
2026-07-01 15:52 ` Darrick J. Wong
2026-07-02 11:05 ` Christoph Hellwig
2026-07-02 15:31 ` Darrick J. Wong
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