Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755404AbaK0Izr (ORCPT ); Thu, 27 Nov 2014 03:55:47 -0500 Received: from mail.kernel.org ([198.145.19.201]:42582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932115AbaK0Iti (ORCPT ); Thu, 27 Nov 2014 03:49:38 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Andrew Morton , Linus Torvalds , Zefan Li Subject: [PATCH 3.4 72/91] perf: fix perf bug in fork() Date: Thu, 27 Nov 2014 16:42:55 +0800 Message-Id: <1417077794-9299-72-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1417077368-9217-1-git-send-email-lizf@kernel.org> References: <1417077368-9217-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra 3.4.105-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 6c72e3501d0d62fc064d3680e5234f3463ec5a86 upstream. Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by calling perf_event_free_task() when failing sched_fork() we will not yet have done the memset() on ->perf_event_ctxp[] and will therefore try and 'free' the inherited contexts, which are still in use by the parent process. This is bad.. Suggested-by: Oleg Nesterov Reported-by: Oleg Nesterov Reported-by: Sylvain 'ythier' Hitier Signed-off-by: Peter Zijlstra (Intel) Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Zefan Li --- kernel/events/core.c | 4 +++- kernel/fork.c | 5 +++-- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index c958be1..10c8fdd 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7127,8 +7127,10 @@ int perf_event_init_task(struct task_struct *child) for_each_task_context_nr(ctxn) { ret = perf_event_init_context(child, ctxn); - if (ret) + if (ret) { + perf_event_free_task(child); return ret; + } } return 0; diff --git a/kernel/fork.c b/kernel/fork.c index 621c547..878dcb2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1285,7 +1285,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, goto bad_fork_cleanup_policy; retval = audit_alloc(p); if (retval) - goto bad_fork_cleanup_policy; + goto bad_fork_cleanup_perf; /* copy all the process information */ retval = copy_semundo(clone_flags, p); if (retval) @@ -1480,8 +1480,9 @@ bad_fork_cleanup_semundo: exit_sem(p); bad_fork_cleanup_audit: audit_free(p); -bad_fork_cleanup_policy: +bad_fork_cleanup_perf: perf_event_free_task(p); +bad_fork_cleanup_policy: #ifdef CONFIG_NUMA mpol_put(p->mempolicy); bad_fork_cleanup_cgroup: -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/