From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 698B2139579; Tue, 4 Feb 2025 01:16:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738631797; cv=none; b=ZdeWDIzZsLA9YzThw49OigT91VtYddm+YeUe7G/lrv1/+7o/+sY6GiVuyYqggS23PPMqBxn/jkI4HDR6PvSe27FK9gtGk1xcvbHRhhqvGFhGqGred5qcIxpRNa2kZE8MbMocWejv911napE/4A8T1rgdw/2ZOQDU/QzY2LpmC3c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738631797; c=relaxed/simple; bh=K/4z85s58YJ+HgdW8rRTJolzJXQ4p1WGU3yjVlV5G90=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ZtoUa/EiD4gWgZQACRET6Pir/wiiL1EddCfT5deXPV2+fVYpYrKcNT993SxW/INy9L6U0k9lgywyASeEZ1xVY13etRIN8IFVtLJs3qbAc6KwzPpuybpYRPH84DCNGJCg6JT23XW/pHfiYQvQxEfjJxxAsLeR4x75gaKDwWEhBrc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bt6Elgmr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bt6Elgmr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9594DC4CEE0; Tue, 4 Feb 2025 01:16:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738631796; bh=K/4z85s58YJ+HgdW8rRTJolzJXQ4p1WGU3yjVlV5G90=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Bt6ElgmriqLfDJRXCZ1ZnA260iRai7Xfaa1992bT3/ZW0aP+GKvJZ8ajEhvWNAwfL FjSBb/lk8F0IUeA8xOG7ibtdQ1+sX+BMAafUnQNk0471/KSAoeC2Nfd55AkEQ6ExnR uYuF/K9qKdc8UoZ89yvbz7gHzA0f4G3Pg7aVtWqS5HHhZAZOeHcXvJEAZbZN5q0qoO RWTvTIvu5hi+wLxo01YLFy3PAb5x3GIxjNo0U9rCpvv51QZzHq397Knd8Qz6yquSFC Q8vWgAOUejmfGzhzgM+uwkm4KCXaq1wAa0zrADqGFegFsO9IUdwzFTCUFMzzOrDZxX vLdrsqbtCb1+Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Maksym Planeta , Juergen Gross , Sasha Levin , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, xen-devel@lists.xenproject.org Subject: [PATCH AUTOSEL 6.13 3/5] Grab mm lock before grabbing pt lock Date: Mon, 3 Feb 2025 20:16:25 -0500 Message-Id: <20250204011627.2206261-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250204011627.2206261-1-sashal@kernel.org> References: <20250204011627.2206261-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.13.1 Content-Transfer-Encoding: 8bit From: Maksym Planeta [ Upstream commit 6d002348789bc16e9203e9818b7a3688787e3b29 ] Function xen_pin_page calls xen_pte_lock, which in turn grab page table lock (ptlock). When locking, xen_pte_lock expect mm->page_table_lock to be held before grabbing ptlock, but this does not happen when pinning is caused by xen_mm_pin_all. This commit addresses lockdep warning below, which shows up when suspending a Xen VM. [ 3680.658422] Freezing user space processes [ 3680.660156] Freezing user space processes completed (elapsed 0.001 seconds) [ 3680.660182] OOM killer disabled. [ 3680.660192] Freezing remaining freezable tasks [ 3680.661485] Freezing remaining freezable tasks completed (elapsed 0.001 seconds) [ 3680.685254] [ 3680.685265] ================================== [ 3680.685269] WARNING: Nested lock was not taken [ 3680.685274] 6.12.0+ #16 Tainted: G W [ 3680.685279] ---------------------------------- [ 3680.685283] migration/0/19 is trying to lock: [ 3680.685288] ffff88800bac33c0 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: xen_pin_page+0x175/0x1d0 [ 3680.685303] [ 3680.685303] but this task is not holding: [ 3680.685308] init_mm.page_table_lock [ 3680.685311] [ 3680.685311] stack backtrace: [ 3680.685316] CPU: 0 UID: 0 PID: 19 Comm: migration/0 Tainted: G W 6.12.0+ #16 [ 3680.685324] Tainted: [W]=WARN [ 3680.685328] Stopper: multi_cpu_stop+0x0/0x120 <- __stop_cpus.constprop.0+0x8c/0xd0 [ 3680.685339] Call Trace: [ 3680.685344] [ 3680.685347] dump_stack_lvl+0x77/0xb0 [ 3680.685356] __lock_acquire+0x917/0x2310 [ 3680.685364] lock_acquire+0xce/0x2c0 [ 3680.685369] ? xen_pin_page+0x175/0x1d0 [ 3680.685373] _raw_spin_lock_nest_lock+0x2f/0x70 [ 3680.685381] ? xen_pin_page+0x175/0x1d0 [ 3680.685386] xen_pin_page+0x175/0x1d0 [ 3680.685390] ? __pfx_xen_pin_page+0x10/0x10 [ 3680.685394] __xen_pgd_walk+0x233/0x2c0 [ 3680.685401] ? stop_one_cpu+0x91/0x100 [ 3680.685405] __xen_pgd_pin+0x5d/0x250 [ 3680.685410] xen_mm_pin_all+0x70/0xa0 [ 3680.685415] xen_pv_pre_suspend+0xf/0x280 [ 3680.685420] xen_suspend+0x57/0x1a0 [ 3680.685428] multi_cpu_stop+0x6b/0x120 [ 3680.685432] ? update_cpumasks_hier+0x7c/0xa60 [ 3680.685439] ? __pfx_multi_cpu_stop+0x10/0x10 [ 3680.685443] cpu_stopper_thread+0x8c/0x140 [ 3680.685448] ? smpboot_thread_fn+0x20/0x1f0 [ 3680.685454] ? __pfx_smpboot_thread_fn+0x10/0x10 [ 3680.685458] smpboot_thread_fn+0xed/0x1f0 [ 3680.685462] kthread+0xde/0x110 [ 3680.685467] ? __pfx_kthread+0x10/0x10 [ 3680.685471] ret_from_fork+0x2f/0x50 [ 3680.685478] ? __pfx_kthread+0x10/0x10 [ 3680.685482] ret_from_fork_asm+0x1a/0x30 [ 3680.685489] [ 3680.685491] [ 3680.685491] other info that might help us debug this: [ 3680.685497] 1 lock held by migration/0/19: [ 3680.685500] #0: ffffffff8284df38 (pgd_lock){+.+.}-{3:3}, at: xen_mm_pin_all+0x14/0xa0 [ 3680.685512] [ 3680.685512] stack backtrace: [ 3680.685518] CPU: 0 UID: 0 PID: 19 Comm: migration/0 Tainted: G W 6.12.0+ #16 [ 3680.685528] Tainted: [W]=WARN [ 3680.685531] Stopper: multi_cpu_stop+0x0/0x120 <- __stop_cpus.constprop.0+0x8c/0xd0 [ 3680.685538] Call Trace: [ 3680.685541] [ 3680.685544] dump_stack_lvl+0x77/0xb0 [ 3680.685549] __lock_acquire+0x93c/0x2310 [ 3680.685554] lock_acquire+0xce/0x2c0 [ 3680.685558] ? xen_pin_page+0x175/0x1d0 [ 3680.685562] _raw_spin_lock_nest_lock+0x2f/0x70 [ 3680.685568] ? xen_pin_page+0x175/0x1d0 [ 3680.685572] xen_pin_page+0x175/0x1d0 [ 3680.685578] ? __pfx_xen_pin_page+0x10/0x10 [ 3680.685582] __xen_pgd_walk+0x233/0x2c0 [ 3680.685588] ? stop_one_cpu+0x91/0x100 [ 3680.685592] __xen_pgd_pin+0x5d/0x250 [ 3680.685596] xen_mm_pin_all+0x70/0xa0 [ 3680.685600] xen_pv_pre_suspend+0xf/0x280 [ 3680.685607] xen_suspend+0x57/0x1a0 [ 3680.685611] multi_cpu_stop+0x6b/0x120 [ 3680.685615] ? update_cpumasks_hier+0x7c/0xa60 [ 3680.685620] ? __pfx_multi_cpu_stop+0x10/0x10 [ 3680.685625] cpu_stopper_thread+0x8c/0x140 [ 3680.685629] ? smpboot_thread_fn+0x20/0x1f0 [ 3680.685634] ? __pfx_smpboot_thread_fn+0x10/0x10 [ 3680.685638] smpboot_thread_fn+0xed/0x1f0 [ 3680.685642] kthread+0xde/0x110 [ 3680.685645] ? __pfx_kthread+0x10/0x10 [ 3680.685649] ret_from_fork+0x2f/0x50 [ 3680.685654] ? __pfx_kthread+0x10/0x10 [ 3680.685657] ret_from_fork_asm+0x1a/0x30 [ 3680.685662] [ 3680.685267] xen:grant_table: Grant tables using version 1 layout [ 3680.685921] OOM killer enabled. [ 3680.685934] Restarting tasks ... done. Signed-off-by: Maksym Planeta Reviewed-by: Juergen Gross Message-ID: <20241204103516.3309112-1-maksym@exostellar.io> Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin --- arch/x86/xen/mmu_pv.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 55a4996d0c04f..2c70cd35e72c5 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -781,6 +781,7 @@ void xen_mm_pin_all(void) { struct page *page; + spin_lock(&init_mm.page_table_lock); spin_lock(&pgd_lock); list_for_each_entry(page, &pgd_list, lru) { @@ -791,6 +792,7 @@ void xen_mm_pin_all(void) } spin_unlock(&pgd_lock); + spin_unlock(&init_mm.page_table_lock); } static void __init xen_mark_pinned(struct mm_struct *mm, struct page *page, @@ -887,6 +889,7 @@ void xen_mm_unpin_all(void) { struct page *page; + spin_lock(&init_mm.page_table_lock); spin_lock(&pgd_lock); list_for_each_entry(page, &pgd_list, lru) { @@ -898,6 +901,7 @@ void xen_mm_unpin_all(void) } spin_unlock(&pgd_lock); + spin_unlock(&init_mm.page_table_lock); } static void xen_enter_mmap(struct mm_struct *mm) -- 2.39.5