The patch titled
ioprio: rcu_read_lock/unlock protect find_task_by_vpid call (V2)
has been added to the -mm tree. Its filename is
ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2.patch
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------------------------------------------------------
Subject: ioprio: rcu_read_lock/unlock protect find_task_by_vpid call (V2)
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Commit 4221a9918e38b7494cee341dda7b7b4bb8c04bde ("Add RCU check for
find_task_by_vpid()") introduced rcu_lockdep_assert to
find_task_by_pid_ns. Assertion failed in sys_ioprio_get. The patch is
fixing assertion failure in ioprio_set as well.
kernel/pid.c:419 invoked rcu_dereference_check() without protection!
stack backtrace:
Pid: 4254, comm: iotop Not tainted
Call Trace:
[<ffffffff810656f2>] lockdep_rcu_dereference+0xaa/0xb2
[<ffffffff81053c67>] find_task_by_pid_ns+0x4f/0x68
[<ffffffff81053c9d>] find_task_by_vpid+0x1d/0x1f
[<ffffffff811104e2>] sys_ioprio_get+0x50/0x2da
[<ffffffff81002182>] system_call_fastpath+0x16/0x1b
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ioprio.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN fs/ioprio.c~ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2 fs/ioprio.c
--- a/fs/ioprio.c~ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2
+++ a/fs/ioprio.c
@@ -106,12 +106,14 @@ SYSCALL_DEFINE3(ioprio_set, int, which,
rcu_read_lock();
switch (which) {
case IOPRIO_WHO_PROCESS:
+ rcu_read_lock();
if (!who)
p = current;
else
p = find_task_by_vpid(who);
if (p)
ret = set_task_ioprio(p, ioprio);
+ rcu_read_unlock();
break;
case IOPRIO_WHO_PGRP:
if (!who)
@@ -195,12 +197,14 @@ SYSCALL_DEFINE2(ioprio_get, int, which,
rcu_read_lock();
switch (which) {
case IOPRIO_WHO_PROCESS:
+ rcu_read_lock();
if (!who)
p = current;
else
p = find_task_by_vpid(who);
if (p)
ret = get_task_ioprio(p);
+ rcu_read_unlock();
break;
case IOPRIO_WHO_PGRP:
if (!who)
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
linux-next.patch
ioprio-rcu_read_lock-unlock-protect-find_task_by_vpid-call-v2.patch
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