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 75117222581; Mon, 23 Jun 2025 22:28:08 +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=1750717688; cv=none; b=Q1ITWOM05ryBMUFPm3J812K5wOYEkrKGjYa7094mmSjhi0cfrkRdszW/eFLMbs9eJmsnes+l1Tn/pciTECiU7lOWhrbIbraQtJ7OrvX77RXQTnA+Ed3gEtjjxnvu+Nu9w2TwajMiduxQnFUGtTFPKupL/Fo5fSYUO5n4nG+/amc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750717688; c=relaxed/simple; bh=HJz0v9++paOruyBaCIh7GIqksMoDO4OWDoLXrdR5kDE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EMXOAB6bSHzSgTj0O8FAKspOakVR6c0zWzdls+7sqvA/WdUJXAlNk3hYGF6/hDoJ+9lRC+o2iP7BvyjBZ0ESh/TNmPNCT+xPsWQKp9V8b+Og2Ctxv27E+uPWA6sfMyb5O1+QJ4zykKBDMC8olLBU6g1lcwoAytBYkpW/DNxT9Ng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pSQgntyU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pSQgntyU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D033C4CEEA; Mon, 23 Jun 2025 22:28:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750717688; bh=HJz0v9++paOruyBaCIh7GIqksMoDO4OWDoLXrdR5kDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pSQgntyUF8LDqWFardv9QXtk7Fjl2Uxr/B8r+UDYS0zh9fdsDtwG4GcPuZZskyYRF CVk1DPUglT46muOeGmZdzBr9tJQs5pwmeJd1c0p2QEiKMQqotmLGAXhTMz8hrY4prH UQBWn8psF+TbHf48/aNuwq1h6I+OscGPs4SkcqXc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Baisheng Gao , Mark Rutland , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 6.1 504/508] perf: Fix sample vs do_exit() Date: Mon, 23 Jun 2025 15:09:09 +0200 Message-ID: <20250623130657.402867158@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250623130645.255320792@linuxfoundation.org> References: <20250623130645.255320792@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra [ Upstream commit 4f6fc782128355931527cefe3eb45338abd8ab39 ] Baisheng Gao reported an ARM64 crash, which Mark decoded as being a synchronous external abort -- most likely due to trying to access MMIO in bad ways. The crash further shows perf trying to do a user stack sample while in exit_mmap()'s tlb_finish_mmu() -- i.e. while tearing down the address space it is trying to access. It turns out that we stop perf after we tear down the userspace mm; a receipie for disaster, since perf likes to access userspace for various reasons. Flip this order by moving up where we stop perf in do_exit(). Additionally, harden PERF_SAMPLE_CALLCHAIN and PERF_SAMPLE_STACK_USER to abort when the current task does not have an mm (exit_mm() makes sure to set current->mm = NULL; before commencing with the actual teardown). Such that CPU wide events don't trip on this same problem. Fixes: c5ebcedb566e ("perf: Add ability to attach user stack dump to sample") Reported-by: Baisheng Gao Suggested-by: Mark Rutland Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20250605110815.GQ39944@noisy.programming.kicks-ass.net Signed-off-by: Sasha Levin --- kernel/events/core.c | 7 +++++++ kernel/exit.c | 17 +++++++++-------- 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 25df8971a56ed..2761db0365ddc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6800,6 +6800,10 @@ perf_sample_ustack_size(u16 stack_size, u16 header_size, if (!regs) return 0; + /* No mm, no stack, no dump. */ + if (!current->mm) + return 0; + /* * Check if we fit in with the requested stack size into the: * - TASK_SIZE @@ -7485,6 +7489,9 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) const u32 max_stack = event->attr.sample_max_stack; struct perf_callchain_entry *callchain; + if (!current->mm) + user = false; + if (!kernel && !user) return &__empty_callchain; diff --git a/kernel/exit.c b/kernel/exit.c index 156283b3c1bf6..10af26a4ab010 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -855,6 +855,15 @@ void __noreturn do_exit(long code) tsk->exit_code = code; taskstats_exit(tsk, group_dead); + /* + * Since sampling can touch ->mm, make sure to stop everything before we + * tear it down. + * + * Also flushes inherited counters to the parent - before the parent + * gets woken up by child-exit notifications. + */ + perf_event_exit_task(tsk); + exit_mm(); if (group_dead) @@ -871,14 +880,6 @@ void __noreturn do_exit(long code) exit_task_work(tsk); exit_thread(tsk); - /* - * Flush inherited counters to the parent - before the parent - * gets woken up by child-exit notifications. - * - * because of cgroup mode, must be called before cgroup_exit() - */ - perf_event_exit_task(tsk); - sched_autogroup_exit_task(tsk); cgroup_exit(tsk); -- 2.39.5