From nobody Sat Nov 23 20:06:32 2024 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 633BD19DF61; Mon, 11 Nov 2024 12:55:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731329703; cv=none; b=rftPnjvbXCGFiWgLbWbQDKim3gydztjFPWYdcBWa+siWZlnbrO+Lt6qPTvyxH3mB9wLQSCi+EkYcZU3097hVk24tMjBMRjIkI/Z6rifvhjiqIfyLpnMs9j+l0iDgRjF7PHkslvMl+7m/1wd9xzq1OTK3Fwp7059X3phwuWHlAMg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731329703; c=relaxed/simple; bh=WL+VTvKdCZu8KF3VGHdzLA4DPkzH0GCIHPSj7kp9giA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GrnIFKF62NQpZGSHdiAGvGje5xpFVnwCTA1MzSSiNY0qJ/Cun871Am8Ox2Fmrkf3ZFymwLbR4p7WvZ+VBrYWYMsonaHI8PiMb3L/ws/T5FjMi4foMmOOT5ociFxY2eB63Vc1BuGQ46+ODRYKWdeO8So1IES4yRNpCoHvf5ANh7U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4Xn8dV5pf8z4f3jR1; Mon, 11 Nov 2024 20:54:38 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id F30971A07B6; Mon, 11 Nov 2024 20:54:56 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.101.6]) by APP4 (Coremail) with SMTP id gCh0CgB3n4Oe_jFnllryBQ--.36628S5; Mon, 11 Nov 2024 20:54:56 +0800 (CST) From: Kemeng Shi To: akpm@linux-foundation.org, willy@infradead.org Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH RESEND V2 3/5] Xarray: move forward index correctly in xas_pause() Date: Tue, 12 Nov 2024 05:53:57 +0800 Message-Id: <20241111215359.246937-4-shikemeng@huaweicloud.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20241111215359.246937-1-shikemeng@huaweicloud.com> References: <20241111215359.246937-1-shikemeng@huaweicloud.com> 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 X-CM-TRANSID: gCh0CgB3n4Oe_jFnllryBQ--.36628S5 X-Coremail-Antispam: 1UD129KBjvJXoWxuFyUWFWxCF4fJFyrAFy5Arb_yoW5Gr1UpF WDGryFyw18Jr1I9rnIqa18uw1Fg3WrKa13trWfGr1ftrZxGr9Fy3Wjkr98XF9xWa18Aa47 CF4rWrn8Ga1DJ3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPFb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M280x2IEY4vEnII2IxkI6r1a6r45M2 8IrcIa0xkI8VA2jI8067AKxVWUWwA2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK 0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW7JVWDJwA2z4 x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l 84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I 8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AK xVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lc7CjxVAaw2AFwI 0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG 67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMI IYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E 14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUaTKu UUUUU X-CM-SenderInfo: 5vklyvpphqwq5kxd4v5lfo033gof0z/ Content-Type: text/plain; charset="utf-8" After xas_load(), xas->index could point to mid of found multi-index entry and xas->index's bits under node->shift maybe non-zero. The afterward xas_pause() will move forward xas->index with xa->node->shift with bits under node->shift un-masked and thus skip some index unexpectedly. Consider following case: Assume XA_CHUNK_SHIFT is 4. xa_store_range(xa, 16, 31, ...) xa_store(xa, 32, ...) XA_STATE(xas, xa, 17); xas_for_each(&xas,...) xas_load(&xas) /* xas->index =3D 17, xas->xa_offset =3D 1, xas->xa_node->xa_shift =3D 4 */ xas_pause() /* xas->index =3D 33, xas->xa_offset =3D 2, xas->xa_node->xa_shift =3D 4 */ As we can see, index of 32 is skipped unexpectedly. Fix this by mask bit under node->xa_shift when move forward index in xas_pause(). Signed-off-by: Kemeng Shi --- lib/test_xarray.c | 35 +++++++++++++++++++++++++++++++++++ lib/xarray.c | 1 + 2 files changed, 36 insertions(+) diff --git a/lib/test_xarray.c b/lib/test_xarray.c index d5c5cbba33ed..6932a26f4927 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1448,6 +1448,41 @@ static noinline void check_pause(struct xarray *xa) XA_BUG_ON(xa, count !=3D order_limit); =20 xa_destroy(xa); + + index =3D 0; + for (order =3D XA_CHUNK_SHIFT; order > 0; order--) { + XA_BUG_ON(xa, xa_store_order(xa, index, order, + xa_mk_index(index), GFP_KERNEL)); + index +=3D 1UL << order; + } + + index =3D 0; + count =3D 0; + xas_set(&xas, 0); + rcu_read_lock(); + xas_for_each(&xas, entry, ULONG_MAX) { + XA_BUG_ON(xa, entry !=3D xa_mk_index(index)); + index +=3D 1UL << (XA_CHUNK_SHIFT - count); + count++; + } + rcu_read_unlock(); + XA_BUG_ON(xa, count !=3D XA_CHUNK_SHIFT); + + index =3D 0; + count =3D 0; + xas_set(&xas, XA_CHUNK_SIZE / 2 + 1); + rcu_read_lock(); + xas_for_each(&xas, entry, ULONG_MAX) { + XA_BUG_ON(xa, entry !=3D xa_mk_index(index)); + index +=3D 1UL << (XA_CHUNK_SHIFT - count); + count++; + xas_pause(&xas); + } + rcu_read_unlock(); + XA_BUG_ON(xa, count !=3D XA_CHUNK_SHIFT); + + xa_destroy(xa); + } =20 static noinline void check_move_tiny(struct xarray *xa) diff --git a/lib/xarray.c b/lib/xarray.c index b9fd321a02ad..3fac3f2cea9d 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1147,6 +1147,7 @@ void xas_pause(struct xa_state *xas) if (!xa_is_sibling(xa_entry(xas->xa, node, offset))) break; } + xas->xa_index &=3D ~0UL << node->shift; xas->xa_index +=3D (offset - xas->xa_offset) << node->shift; if (xas->xa_index =3D=3D 0) xas->xa_node =3D XAS_BOUNDS; --=20 2.30.0