From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "Michal Koutný" <mkoutny@suse.com>,
"Suren Baghdasaryan" <surenb@google.com>,
"Tejun Heo" <tj@kernel.org>, "Sasha Levin" <sashal@kernel.org>,
cgroups@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 02/37] cgroup: Iterate tasks that did not finish do_exit()
Date: Wed, 18 Mar 2020 16:54:34 -0400 [thread overview]
Message-ID: <20200318205509.17053-2-sashal@kernel.org> (raw)
In-Reply-To: <20200318205509.17053-1-sashal@kernel.org>
From: Michal Koutný <mkoutny@suse.com>
[ Upstream commit 9c974c77246460fa6a92c18554c3311c8c83c160 ]
PF_EXITING is set earlier than actual removal from css_set when a task
is exitting. This can confuse cgroup.procs readers who see no PF_EXITING
tasks, however, rmdir is checking against css_set membership so it can
transitionally fail with EBUSY.
Fix this by listing tasks that weren't unlinked from css_set active
lists.
It may happen that other users of the task iterator (without
CSS_TASK_ITER_PROCS) spot a PF_EXITING task before cgroup_exit(). This
is equal to the state before commit c03cd7738a83 ("cgroup: Include dying
leaders with live threads in PROCS iterations") but it may be reviewed
later.
Reported-by: Suren Baghdasaryan <surenb@google.com>
Fixes: c03cd7738a83 ("cgroup: Include dying leaders with live threads in PROCS iterations")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/cgroup.h | 1 +
kernel/cgroup/cgroup.c | 23 ++++++++++++++++-------
2 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b4854b48a4f3d..5ed1a2b285cdd 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -62,6 +62,7 @@ struct css_task_iter {
struct list_head *mg_tasks_head;
struct list_head *dying_tasks_head;
+ struct list_head *cur_tasks_head;
struct css_set *cur_cset;
struct css_set *cur_dcset;
struct task_struct *cur_task;
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 08bd40d900660..c416ef3e34797 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4157,12 +4157,16 @@ static void css_task_iter_advance_css_set(struct css_task_iter *it)
}
} while (!css_set_populated(cset) && list_empty(&cset->dying_tasks));
- if (!list_empty(&cset->tasks))
+ if (!list_empty(&cset->tasks)) {
it->task_pos = cset->tasks.next;
- else if (!list_empty(&cset->mg_tasks))
+ it->cur_tasks_head = &cset->tasks;
+ } else if (!list_empty(&cset->mg_tasks)) {
it->task_pos = cset->mg_tasks.next;
- else
+ it->cur_tasks_head = &cset->mg_tasks;
+ } else {
it->task_pos = cset->dying_tasks.next;
+ it->cur_tasks_head = &cset->dying_tasks;
+ }
it->tasks_head = &cset->tasks;
it->mg_tasks_head = &cset->mg_tasks;
@@ -4220,10 +4224,14 @@ static void css_task_iter_advance(struct css_task_iter *it)
else
it->task_pos = it->task_pos->next;
- if (it->task_pos == it->tasks_head)
+ if (it->task_pos == it->tasks_head) {
it->task_pos = it->mg_tasks_head->next;
- if (it->task_pos == it->mg_tasks_head)
+ it->cur_tasks_head = it->mg_tasks_head;
+ }
+ if (it->task_pos == it->mg_tasks_head) {
it->task_pos = it->dying_tasks_head->next;
+ it->cur_tasks_head = it->dying_tasks_head;
+ }
if (it->task_pos == it->dying_tasks_head)
css_task_iter_advance_css_set(it);
} else {
@@ -4242,11 +4250,12 @@ static void css_task_iter_advance(struct css_task_iter *it)
goto repeat;
/* and dying leaders w/o live member threads */
- if (!atomic_read(&task->signal->live))
+ if (it->cur_tasks_head == it->dying_tasks_head &&
+ !atomic_read(&task->signal->live))
goto repeat;
} else {
/* skip all dying ones */
- if (task->flags & PF_EXITING)
+ if (it->cur_tasks_head == it->dying_tasks_head)
goto repeat;
}
}
--
2.20.1
next prev parent reply other threads:[~2020-03-18 21:04 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 20:54 [PATCH AUTOSEL 4.19 01/37] cgroup-v1: cgroup_pidlist_next should update position index Sasha Levin
2020-03-18 20:54 ` Sasha Levin [this message]
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 03/37] batman-adv: Don't schedule OGM for disabled interface Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 04/37] pinctrl: meson-gxl: fix GPIOX sdio pins Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 05/37] nfs: add minor version to nfs_server_key for fscache Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 06/37] pinctrl: core: Remove extra kref_get which blocks hogs being freed Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 07/37] r8152: check disconnect status after long sleep Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 08/37] bnxt_en: reinitialize IRQs when MTU is modified Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 09/37] cpupower: avoid multiple definition with gcc -fno-common Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 10/37] fib: add missing attribute validation for tun_id Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 11/37] can: add missing attribute validation for termination Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 12/37] macsec: add missing attribute validation for port Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 13/37] team: add missing attribute validation for port ifindex Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 14/37] team: add missing attribute validation for array index Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 15/37] netfilter: cthelper: add missing attribute validation for cthelper Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 16/37] netfilter: nft_payload: add missing attribute validation for payload csum flags Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 17/37] netfilter: nft_tunnel: add missing attribute validation for tunnels Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 18/37] drivers/of/of_mdio.c:fix of_mdiobus_register() Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 19/37] cgroup1: don't call release_agent when it is "" Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 20/37] dt-bindings: net: FMan erratum A050385 Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 21/37] arm64: dts: ls1043a: " Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 22/37] fsl/fman: detect " Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 23/37] virtio-blk: fix hw_queue stopped on arbitrary error Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 24/37] ipvlan: do not add hardware address of master to its unicast filter list Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 25/37] net: stmmac: dwmac1000: Disable ACS if enhanced descs are not used Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 26/37] ipvlan: don't deref eth hdr before checking it's set Sasha Levin
2020-03-18 20:54 ` [PATCH AUTOSEL 4.19 27/37] ipvlan: add cond_resched_rcu() while processing muticast backlog Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 28/37] ipvlan: do not use cond_resched_rcu() in ipvlan_process_multicast() Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 29/37] i2c: gpio: suppress error on probe defer Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 30/37] s390/qeth: handle error when backing RX buffer Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 31/37] scsi: ipr: Fix softlockup when rescanning devices in petitboot Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 32/37] mac80211: Do not send mesh HWMP PREQ if HWMP is disabled Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 33/37] dpaa_eth: Remove unnecessary boolean expression in dpaa_get_headroom Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 34/37] sxgbe: Fix off by one in samsung driver strncpy size arg Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 35/37] net: systemport: fix index check to avoid an array out of bounds access Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 36/37] iommu/vt-d: quirk_ioat_snb_local_iommu: replace WARN_TAINT with pr_warn + add_taint Sasha Levin
2020-03-18 20:55 ` [PATCH AUTOSEL 4.19 37/37] iommu/vt-d: Fix the wrong printing in RHSA parsing Sasha Levin
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