From nobody Wed Dec 17 08:58:38 2025 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (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 DDC438C0B for ; Fri, 12 Jul 2024 03:17:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.255 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720754268; cv=none; b=ITY3qTZv+dkceMaKHxwmIdXPUv+kKx/B4vYqmIckLBvEzBk+HQOD7Tbg2csYAaBRKvxEUPiuK+MA4zbwnEAhynT+EVg1h4QkiRGElVjpgm2gEdNlZQlaGawhcqDUAg59OpwxMU9362LROJFzAWORcB4KZRwVspMVpCutnJqxOZ4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720754268; c=relaxed/simple; bh=wKaF5l1dx+R5sG0MMIZb0tHr9Pcg1um8n4IFlhsUwJ0=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=LZuQm69E765Ihgm7X1bw9dSU+g47GjIvh4bfkkaxwiFSGP/HVyPM0wrppWTFs8XhNSMZEoxvkgWuVSwg1YWjRUFOtKAly7SmKCUPEzJnXEWu5CEHAOUmh6wJuDqMXHk3yfepsd/cfhyBFUh+tVwqS3hpY0YdiYL5lR72Xu64iuY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.255 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4WKxVd2l1Dz1T67S; Fri, 12 Jul 2024 11:12:57 +0800 (CST) Received: from kwepemd200019.china.huawei.com (unknown [7.221.188.193]) by mail.maildlp.com (Postfix) with ESMTPS id 2547818009B; Fri, 12 Jul 2024 11:17:42 +0800 (CST) Received: from huawei.com (10.173.127.72) by kwepemd200019.china.huawei.com (7.221.188.193) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 12 Jul 2024 11:17:41 +0800 From: Miaohe Lin To: , CC: , , Subject: [PATCH v2] mm/hugetlb: fix possible recursive locking detected warning Date: Fri, 12 Jul 2024 11:13:14 +0800 Message-ID: <20240712031314.2570452-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.33.0 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-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemd200019.china.huawei.com (7.221.188.193) Content-Type: text/plain; charset="utf-8" When tries to demote 1G hugetlb folios, a lockdep warning is observed: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D WARNING: possible recursive locking detected 6.10.0-rc6-00452-ga4d0275fa660-dirty #79 Not tainted Acked-by: Muchun Song -------------------------------------------- bash/710 is trying to acquire lock: ffffffff8f0a7850 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0x244/0x460 but task is already holding lock: ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0xae/0x460 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&h->resize_lock); lock(&h->resize_lock); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by bash/710: #0: ffff8f118439c3f0 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x64/0xe0 #1: ffff8f11893b9e88 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter= +0xf8/0x1d0 #2: ffff8f1183dc4428 (kn->active#98){.+.+}-{0:0}, at: kernfs_fop_write_ite= r+0x100/0x1d0 #3: ffffffff8f0a6f48 (&h->resize_lock){+.+.}-{3:3}, at: demote_store+0xae/= 0x460 stack backtrace: CPU: 3 PID: 710 Comm: bash Not tainted 6.10.0-rc6-00452-ga4d0275fa660-dirty= #79 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g1= 55821a1990b-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x68/0xa0 __lock_acquire+0x10f2/0x1ca0 lock_acquire+0xbe/0x2d0 __mutex_lock+0x6d/0x400 demote_store+0x244/0x460 kernfs_fop_write_iter+0x12c/0x1d0 vfs_write+0x380/0x540 ksys_write+0x64/0xe0 do_syscall_64+0xb9/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa61db14887 RSP: 002b:00007ffc56c48358 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fa61db14887 RDX: 0000000000000002 RSI: 000055a030050220 RDI: 0000000000000001 RBP: 000055a030050220 R08: 00007fa61dbd1460 R09: 000000007fffffff R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007fa61dc1b780 R14: 00007fa61dc17600 R15: 00007fa61dc16a00 Lockdep considers this an AA deadlock because the different resize_lock mutexes reside in the same lockdep class, but this is a false positive. Place them in distinct classes to avoid these warnings. Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support") Signed-off-by: Miaohe Lin --- v2: move lock_class_key into struct hstate and use __mutex_init per Muchun. Thanks. --- include/linux/hugetlb.h | 1 + mm/hugetlb.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 98c2c1106500..b84da6f6ac40 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -649,6 +649,7 @@ HPAGEFLAG(RawHwpUnreliable, raw_hwp_unreliable) /* Defines one hugetlb page size */ struct hstate { struct mutex resize_lock; + struct lock_class_key resize_key; int next_nid_to_alloc; int next_nid_to_free; unsigned int order; diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 45fd3bc75332..926b89e165bd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4670,7 +4670,7 @@ void __init hugetlb_add_hstate(unsigned int order) BUG_ON(hugetlb_max_hstate >=3D HUGE_MAX_HSTATE); BUG_ON(order < order_base_2(__NR_USED_SUBPAGE)); h =3D &hstates[hugetlb_max_hstate++]; - mutex_init(&h->resize_lock); + __mutex_init(&h->resize_lock, "resize mutex", &h->resize_key); h->order =3D order; h->mask =3D ~(huge_page_size(h) - 1); for (i =3D 0; i < MAX_NUMNODES; ++i) --=20 2.33.0