* [PATCH AUTOSEL 4.14 04/99] ipc: prevent lockup on alloc_msg and free_msg
[not found] <20190601132346.26558-1-sashal@kernel.org>
@ 2019-06-01 13:22 ` Sasha Levin
2019-06-01 13:22 ` [PATCH AUTOSEL 4.14 31/99] percpu: remove spurious lock dependency between percpu and sched Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2019-06-01 13:22 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Li Rongqing, Zhang Yu, Davidlohr Bueso, Manfred Spraul,
Arnd Bergmann, Andrew Morton, Linus Torvalds, Sasha Levin, netdev,
bpf
From: Li Rongqing <lirongqing@baidu.com>
[ Upstream commit d6a2946a88f524a47cc9b79279667137899db807 ]
msgctl10 of ltp triggers the following lockup When CONFIG_KASAN is
enabled on large memory SMP systems, the pages initialization can take a
long time, if msgctl10 requests a huge block memory, and it will block
rcu scheduler, so release cpu actively.
After adding schedule() in free_msg, free_msg can not be called when
holding spinlock, so adding msg to a tmp list, and free it out of
spinlock
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-1 rcu_node (CPUs 16-31): P32505
rcu: Tasks blocked on level-1 rcu_node (CPUs 48-63): P34978
rcu: (detected by 11, t=35024 jiffies, g=44237529, q=16542267)
msgctl10 R running task 21608 32505 2794 0x00000082
Call Trace:
preempt_schedule_irq+0x4c/0xb0
retint_kernel+0x1b/0x2d
RIP: 0010:__is_insn_slot_addr+0xfb/0x250
Code: 82 1d 00 48 8b 9b 90 00 00 00 4c 89 f7 49 c1 ee 03 e8 59 83 1d 00 48 b8 00 00 00 00 00 fc ff df 4c 39 eb 48 89 9d 58 ff ff ff <41> c6 04 06 f8 74 66 4c 8d 75 98 4c 89 f1 48 c1 e9 03 48 01 c8 48
RSP: 0018:ffff88bce041f758 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffffffff8471bc50 RCX: ffffffff828a2a57
RDX: dffffc0000000000 RSI: dffffc0000000000 RDI: ffff88bce041f780
RBP: ffff88bce041f828 R08: ffffed15f3f4c5b3 R09: ffffed15f3f4c5b3
R10: 0000000000000001 R11: ffffed15f3f4c5b2 R12: 000000318aee9b73
R13: ffffffff8471bc50 R14: 1ffff1179c083ef0 R15: 1ffff1179c083eec
kernel_text_address+0xc1/0x100
__kernel_text_address+0xe/0x30
unwind_get_return_address+0x2f/0x50
__save_stack_trace+0x92/0x100
create_object+0x380/0x650
__kmalloc+0x14c/0x2b0
load_msg+0x38/0x1a0
do_msgsnd+0x19e/0xcf0
do_syscall_64+0x117/0x400
entry_SYSCALL_64_after_hwframe+0x49/0xbe
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-1 rcu_node (CPUs 0-15): P32170
rcu: (detected by 14, t=35016 jiffies, g=44237525, q=12423063)
msgctl10 R running task 21608 32170 32155 0x00000082
Call Trace:
preempt_schedule_irq+0x4c/0xb0
retint_kernel+0x1b/0x2d
RIP: 0010:lock_acquire+0x4d/0x340
Code: 48 81 ec c0 00 00 00 45 89 c6 4d 89 cf 48 8d 6c 24 20 48 89 3c 24 48 8d bb e4 0c 00 00 89 74 24 0c 48 c7 44 24 20 b3 8a b5 41 <48> c1 ed 03 48 c7 44 24 28 b4 25 18 84 48 c7 44 24 30 d0 54 7a 82
RSP: 0018:ffff88af83417738 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffff88bd335f3080 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88bd335f3d64
RBP: ffff88af83417758 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: ffffed13f3f745b2 R12: 0000000000000000
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
is_bpf_text_address+0x32/0xe0
kernel_text_address+0xec/0x100
__kernel_text_address+0xe/0x30
unwind_get_return_address+0x2f/0x50
__save_stack_trace+0x92/0x100
save_stack+0x32/0xb0
__kasan_slab_free+0x130/0x180
kfree+0xfa/0x2d0
free_msg+0x24/0x50
do_msgrcv+0x508/0xe60
do_syscall_64+0x117/0x400
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Davidlohr said:
"So after releasing the lock, the msg rbtree/list is empty and new
calls will not see those in the newly populated tmp_msg list, and
therefore they cannot access the delayed msg freeing pointers, which
is good. Also the fact that the node_cache is now freed before the
actual messages seems to be harmless as this is wanted for
msg_insert() avoiding GFP_ATOMIC allocations, and after releasing the
info->lock the thing is freed anyway so it should not change things"
Link: http://lkml.kernel.org/r/1552029161-4957-1-git-send-email-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
ipc/mqueue.c | 10 ++++++++--
ipc/msgutil.c | 6 ++++++
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index d240256263103..5c0ae912f2f25 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -374,7 +374,8 @@ static void mqueue_evict_inode(struct inode *inode)
struct user_struct *user;
unsigned long mq_bytes, mq_treesize;
struct ipc_namespace *ipc_ns;
- struct msg_msg *msg;
+ struct msg_msg *msg, *nmsg;
+ LIST_HEAD(tmp_msg);
clear_inode(inode);
@@ -385,10 +386,15 @@ static void mqueue_evict_inode(struct inode *inode)
info = MQUEUE_I(inode);
spin_lock(&info->lock);
while ((msg = msg_get(info)) != NULL)
- free_msg(msg);
+ list_add_tail(&msg->m_list, &tmp_msg);
kfree(info->node_cache);
spin_unlock(&info->lock);
+ list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
+ list_del(&msg->m_list);
+ free_msg(msg);
+ }
+
/* Total amount of bytes accounted for the mqueue */
mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index 84598025a6ade..e65593742e2be 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -18,6 +18,7 @@
#include <linux/utsname.h>
#include <linux/proc_ns.h>
#include <linux/uaccess.h>
+#include <linux/sched.h>
#include "util.h"
@@ -64,6 +65,9 @@ static struct msg_msg *alloc_msg(size_t len)
pseg = &msg->next;
while (len > 0) {
struct msg_msgseg *seg;
+
+ cond_resched();
+
alen = min(len, DATALEN_SEG);
seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
if (seg == NULL)
@@ -176,6 +180,8 @@ void free_msg(struct msg_msg *msg)
kfree(msg);
while (seg != NULL) {
struct msg_msgseg *tmp = seg->next;
+
+ cond_resched();
kfree(seg);
seg = tmp;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH AUTOSEL 4.14 31/99] percpu: remove spurious lock dependency between percpu and sched
[not found] <20190601132346.26558-1-sashal@kernel.org>
2019-06-01 13:22 ` [PATCH AUTOSEL 4.14 04/99] ipc: prevent lockup on alloc_msg and free_msg Sasha Levin
@ 2019-06-01 13:22 ` Sasha Levin
1 sibling, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2019-06-01 13:22 UTC (permalink / raw)
To: linux-kernel, stable
Cc: John Sperbeck, Dennis Zhou, Sasha Levin, linux-mm, netdev, bpf
From: John Sperbeck <jsperbeck@google.com>
[ Upstream commit 198790d9a3aeaef5792d33a560020861126edc22 ]
In free_percpu() we sometimes call pcpu_schedule_balance_work() to
queue a work item (which does a wakeup) while holding pcpu_lock.
This creates an unnecessary lock dependency between pcpu_lock and
the scheduler's pi_lock. There are other places where we call
pcpu_schedule_balance_work() without hold pcpu_lock, and this case
doesn't need to be different.
Moving the call outside the lock prevents the following lockdep splat
when running tools/testing/selftests/bpf/{test_maps,test_progs} in
sequence with lockdep enabled:
======================================================
WARNING: possible circular locking dependency detected
5.1.0-dbg-DEV #1 Not tainted
------------------------------------------------------
kworker/23:255/18872 is trying to acquire lock:
000000000bc79290 (&(&pool->lock)->rlock){-.-.}, at: __queue_work+0xb2/0x520
but task is already holding lock:
00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (pcpu_lock){..-.}:
lock_acquire+0x9e/0x180
_raw_spin_lock_irqsave+0x3a/0x50
pcpu_alloc+0xfa/0x780
__alloc_percpu_gfp+0x12/0x20
alloc_htab_elem+0x184/0x2b0
__htab_percpu_map_update_elem+0x252/0x290
bpf_percpu_hash_update+0x7c/0x130
__do_sys_bpf+0x1912/0x1be0
__x64_sys_bpf+0x1a/0x20
do_syscall_64+0x59/0x400
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #3 (&htab->buckets[i].lock){....}:
lock_acquire+0x9e/0x180
_raw_spin_lock_irqsave+0x3a/0x50
htab_map_update_elem+0x1af/0x3a0
-> #2 (&rq->lock){-.-.}:
lock_acquire+0x9e/0x180
_raw_spin_lock+0x2f/0x40
task_fork_fair+0x37/0x160
sched_fork+0x211/0x310
copy_process.part.43+0x7b1/0x2160
_do_fork+0xda/0x6b0
kernel_thread+0x29/0x30
rest_init+0x22/0x260
arch_call_rest_init+0xe/0x10
start_kernel+0x4fd/0x520
x86_64_start_reservations+0x24/0x26
x86_64_start_kernel+0x6f/0x72
secondary_startup_64+0xa4/0xb0
-> #1 (&p->pi_lock){-.-.}:
lock_acquire+0x9e/0x180
_raw_spin_lock_irqsave+0x3a/0x50
try_to_wake_up+0x41/0x600
wake_up_process+0x15/0x20
create_worker+0x16b/0x1e0
workqueue_init+0x279/0x2ee
kernel_init_freeable+0xf7/0x288
kernel_init+0xf/0x180
ret_from_fork+0x24/0x30
-> #0 (&(&pool->lock)->rlock){-.-.}:
__lock_acquire+0x101f/0x12a0
lock_acquire+0x9e/0x180
_raw_spin_lock+0x2f/0x40
__queue_work+0xb2/0x520
queue_work_on+0x38/0x80
free_percpu+0x221/0x260
pcpu_freelist_destroy+0x11/0x20
stack_map_free+0x2a/0x40
bpf_map_free_deferred+0x3c/0x50
process_one_work+0x1f7/0x580
worker_thread+0x54/0x410
kthread+0x10f/0x150
ret_from_fork+0x24/0x30
other info that might help us debug this:
Chain exists of:
&(&pool->lock)->rlock --> &htab->buckets[i].lock --> pcpu_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(pcpu_lock);
lock(&htab->buckets[i].lock);
lock(pcpu_lock);
lock(&(&pool->lock)->rlock);
*** DEADLOCK ***
3 locks held by kworker/23:255/18872:
#0: 00000000b36a6e16 ((wq_completion)events){+.+.},
at: process_one_work+0x17a/0x580
#1: 00000000dfd966f0 ((work_completion)(&map->work)){+.+.},
at: process_one_work+0x17a/0x580
#2: 00000000e3e7a6aa (pcpu_lock){..-.},
at: free_percpu+0x36/0x260
stack backtrace:
CPU: 23 PID: 18872 Comm: kworker/23:255 Not tainted 5.1.0-dbg-DEV #1
Hardware name: ...
Workqueue: events bpf_map_free_deferred
Call Trace:
dump_stack+0x67/0x95
print_circular_bug.isra.38+0x1c6/0x220
check_prev_add.constprop.50+0x9f6/0xd20
__lock_acquire+0x101f/0x12a0
lock_acquire+0x9e/0x180
_raw_spin_lock+0x2f/0x40
__queue_work+0xb2/0x520
queue_work_on+0x38/0x80
free_percpu+0x221/0x260
pcpu_freelist_destroy+0x11/0x20
stack_map_free+0x2a/0x40
bpf_map_free_deferred+0x3c/0x50
process_one_work+0x1f7/0x580
worker_thread+0x54/0x410
kthread+0x10f/0x150
ret_from_fork+0x24/0x30
Signed-off-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/percpu.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 0c06e2f549a7b..bc58bcbe4b609 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1702,6 +1702,7 @@ void free_percpu(void __percpu *ptr)
struct pcpu_chunk *chunk;
unsigned long flags;
int off;
+ bool need_balance = false;
if (!ptr)
return;
@@ -1723,7 +1724,7 @@ void free_percpu(void __percpu *ptr)
list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
if (pos != chunk) {
- pcpu_schedule_balance_work();
+ need_balance = true;
break;
}
}
@@ -1731,6 +1732,9 @@ void free_percpu(void __percpu *ptr)
trace_percpu_free_percpu(chunk->base_addr, off, ptr);
spin_unlock_irqrestore(&pcpu_lock, flags);
+
+ if (need_balance)
+ pcpu_schedule_balance_work();
}
EXPORT_SYMBOL_GPL(free_percpu);
--
2.20.1
^ permalink raw reply related [flat|nested] 2+ messages in thread