From nobody Wed Feb 11 13:27:57 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D47036A33B; Wed, 28 May 2025 11:31:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748431920; cv=none; b=iYoEnsP1eQ3bB9VfPm1tyZsisnCuOoZiMG3RDihgJUMjdDjTrYYjiYE0j/OGKXxLFzCnLGI/K5u/ezkf3VytvBCaT4GNUos2a2KymqMIqhvTaQqfT3obbT+tLORD7Feh9yRL5ni39N5nkr25oW43V5KFmXfdQQADC9cIOrslaJQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748431920; c=relaxed/simple; bh=M28L9NabqiiiSMq+L/jI0962Wz2oEsat/29mEBFseHU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=YuV7YiVqwa3J8q1/EBvRZa0gC8pCD0Qm1zWEzG9dmeh3LZOdPizlntYm+YMXg+xq+V9qNEJYSVZPFGrPDATmzaSAgGHeoSkyFpaaOwn7RKP/QtrKBPlbjpucE55S32f7tSg6qVGbrXbxYAOwCECds6g7HQA7yYdtDQW6NSf2Ftk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9F7621A25; Wed, 28 May 2025 04:31:40 -0700 (PDT) Received: from MacBook-Pro.blr.arm.com (unknown [10.164.18.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8666B3F5A1; Wed, 28 May 2025 04:31:54 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org, willy@infradead.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com, anshuman.khandual@arm.com, ryan.roberts@arm.com, Dev Jain Subject: [PATCH] xarray: Add a BUG_ON() to ensure caller is not sibling Date: Wed, 28 May 2025 17:01:24 +0530 Message-Id: <20250528113124.87084-1-dev.jain@arm.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Suppose xas is pointing somewhere near the end of the multi-entry batch. Then it may happen that the computed slot already falls beyond the batch, thus breaking the loop due to !xa_is_sibling(), and computing the wrong order. Thus ensure that the caller is aware of this by triggering a BUG when the entry is a sibling entry. This patch is motivated by code inspection and not a real bug report. Signed-off-by: Dev Jain --- The patch applies on 6.15 kernel. lib/xarray.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/xarray.c b/lib/xarray.c index 9644b18af18d..0f699766c24f 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1917,6 +1917,8 @@ int xas_get_order(struct xa_state *xas) if (!xas->xa_node) return 0; =20 + XA_NODE_BUG_ON(xas->xa_node, xa_is_sibling(xa_entry(xas->xa, + xas->xa_node, xas->xa_offset))); for (;;) { unsigned int slot =3D xas->xa_offset + (1 << order); =20 --=20 2.30.2