From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
alan@lxorguk.ukuu.org.uk, Tejun Heo <tj@kernel.org>,
Li Zefan <lizefan@huawei.com>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: [ 21/42] Revert "cgroup: Remove task_lock() from cgroup_post_fork()"
Date: Thu, 25 Oct 2012 17:05:29 -0700 [thread overview]
Message-ID: <20121026000126.914584418@linuxfoundation.org> (raw)
In-Reply-To: <20121026000124.790781113@linuxfoundation.org>
3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tejun Heo <tj@kernel.org>
commit d87838321124061f6c935069d97f37010fa417e6 upstream.
This reverts commit 7e3aa30ac8c904a706518b725c451bb486daaae9.
The commit incorrectly assumed that fork path always performed
threadgroup_change_begin/end() and depended on that for
synchronization against task exit and cgroup migration paths instead
of explicitly grabbing task_lock().
threadgroup_change is not locked when forking a new process (as
opposed to a new thread in the same process) and even if it were it
wouldn't be effective as different processes use different threadgroup
locks.
Revert the incorrect optimization.
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <20121008020000.GB2575@localhost>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/cgroup.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4539,19 +4539,10 @@ void cgroup_post_fork(struct task_struct
*/
if (use_task_css_set_links) {
write_lock(&css_set_lock);
- if (list_empty(&child->cg_list)) {
- /*
- * It's safe to use child->cgroups without task_lock()
- * here because we are protected through
- * threadgroup_change_begin() against concurrent
- * css_set change in cgroup_task_migrate(). Also
- * the task can't exit at that point until
- * wake_up_new_task() is called, so we are protected
- * against cgroup_exit() setting child->cgroup to
- * init_css_set.
- */
+ task_lock(child);
+ if (list_empty(&child->cg_list))
list_add(&child->cg_list, &child->cgroups->tasks);
- }
+ task_unlock(child);
write_unlock(&css_set_lock);
}
}
next prev parent reply other threads:[~2012-10-26 0:39 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-26 0:05 [ 00/42] 3.4.16-stable review Greg Kroah-Hartman
2012-10-26 0:05 ` [ 01/42] ext4: race-condition protection for ext4_convert_unwritten_extents_endio Greg Kroah-Hartman
2012-10-26 0:05 ` [ 02/42] ext4: Avoid underflow in ext4_trim_fs() Greg Kroah-Hartman
2012-10-26 0:05 ` [ 03/42] nohz: Fix idle ticks in cpu summary line of /proc/stat Greg Kroah-Hartman
2012-10-26 0:05 ` [ 04/42] arch/tile: avoid generating .eh_frame information in modules Greg Kroah-Hartman
2012-10-26 0:05 ` [ 05/42] NLM: nlm_lookup_file() may return NLMv4-specific error codes Greg Kroah-Hartman
2012-10-26 0:05 ` [ 06/42] oprofile, x86: Fix wrapping bug in op_x86_get_ctrl() Greg Kroah-Hartman
2012-10-26 0:05 ` [ 07/42] s390: fix linker script for 31 bit builds Greg Kroah-Hartman
2012-10-26 0:05 ` [ 08/42] SUNRPC: Prevent kernel stack corruption on long values of flush Greg Kroah-Hartman
2012-10-26 0:05 ` [ 09/42] SUNRPC: Fix a UDP transport regression Greg Kroah-Hartman
2012-10-26 0:05 ` [ 10/42] pcmcia: sharpsl: dont discard sharpsl_pcmcia_ops Greg Kroah-Hartman
2012-10-26 0:05 ` [ 11/42] kernel/sys.c: fix stack memory content leak via UNAME26 Greg Kroah-Hartman
2012-10-26 0:05 ` [ 12/42] use clamp_t in UNAME26 fix Greg Kroah-Hartman
2012-10-26 0:05 ` [ 13/42] x86: Exclude E820_RESERVED regions and memory holes above 4 GB from direct mapping Greg Kroah-Hartman
2012-10-26 0:05 ` [ 14/42] xen/x86: dont corrupt %eip when returning from a signal handler Greg Kroah-Hartman
2012-10-26 0:05 ` [ 15/42] USB: cdc-acm: fix pipe type of write endpoint Greg Kroah-Hartman
2012-10-26 0:05 ` [ 16/42] usb: acm: fix the computation of the number of data bits Greg Kroah-Hartman
2012-10-26 0:05 ` [ 17/42] usb: host: xhci: New system added for Compliance Mode Patch on SN65LVPE502CP Greg Kroah-Hartman
2012-10-26 0:05 ` [ 18/42] USB: option: blacklist net interface on ZTE devices Greg Kroah-Hartman
2012-10-26 0:05 ` [ 19/42] USB: option: add more " Greg Kroah-Hartman
2012-10-26 0:05 ` [ 20/42] cgroup: notify_on_release may not be triggered in some cases Greg Kroah-Hartman
2012-10-26 0:05 ` Greg Kroah-Hartman [this message]
2012-10-26 0:05 ` [ 22/42] Revert "cgroup: Drop task_lock(parent) on cgroup_fork()" Greg Kroah-Hartman
2012-10-26 0:05 ` [ 23/42] pinctrl: tegra: correct bank for pingroup and drv pingroup Greg Kroah-Hartman
2012-10-26 0:05 ` [ 24/42] pinctrl: tegra: set low power mode bank width to 2 Greg Kroah-Hartman
2012-10-26 0:05 ` [ 25/42] iommu/tegra: smmu: Fix deadly typo Greg Kroah-Hartman
2012-10-26 0:05 ` [ 26/42] amd64_edac:__amd64_set_scrub_rate(): avoid overindexing scrubrates[] Greg Kroah-Hartman
2012-10-26 0:05 ` [ 27/42] usb: dwc3: gadget: fix endpoint always busy bug Greg Kroah-Hartman
2012-10-26 0:05 ` [ 28/42] media: au0828: fix case where STREAMOFF being called on stopped stream causes BUG() Greg Kroah-Hartman
2012-10-26 0:05 ` [ 29/42] netlink: add reference of module in netlink_dump_start Greg Kroah-Hartman
2012-10-26 0:05 ` [ 30/42] infiniband: pass rdma_cm module to netlink_dump_start Greg Kroah-Hartman
2012-10-26 0:05 ` [ 31/42] net: Fix skb_under_panic oops in neigh_resolve_output Greg Kroah-Hartman
2012-10-26 0:05 ` [ 32/42] skge: Add DMA mask quirk for Marvell 88E8001 on ASUS P5NSLI motherboard Greg Kroah-Hartman
2012-10-26 0:05 ` [ 33/42] vlan: dont deliver frames for unknown vlans to protocols Greg Kroah-Hartman
2012-10-26 0:05 ` [ 34/42] RDS: fix rds-ping spinlock recursion Greg Kroah-Hartman
2012-10-26 0:05 ` [ 35/42] tcp: resets are misrouted Greg Kroah-Hartman
2012-10-26 0:05 ` [ 36/42] ipv6: addrconf: fix /proc/net/if_inet6 Greg Kroah-Hartman
2012-10-26 0:05 ` [ 37/42] sparc64: fix ptrace interaction with force_successful_syscall_return() Greg Kroah-Hartman
2012-10-26 0:05 ` [ 38/42] sparc64: Like x86 we should check current->mm during perf backtrace generation Greg Kroah-Hartman
2012-10-26 0:05 ` [ 39/42] sparc64: Fix bit twiddling in sparc_pmu_enable_event() Greg Kroah-Hartman
2012-10-26 0:05 ` [ 40/42] sparc64: do not clobber personality flags in sys_sparc64_personality() Greg Kroah-Hartman
2012-10-26 0:05 ` [ 41/42] sparc64: Be less verbose during vmemmap population Greg Kroah-Hartman
2012-10-26 0:05 ` [ 42/42] mtd: nand: allow NAND_NO_SUBPAGE_WRITE to be set from driver Greg Kroah-Hartman
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