On 1/18/2019 2:57 PM, Li RongQing wrote:
There still is a race window after the commit b027e2298bd588
("tty: fix data race between tty_init_dev and flush of buf"),
and we encountered this crash issue if receive_buf call comes
before tty initialization completes in n_tty_open and
tty->driver_da
deactivate_task(rq, prev, DEQUEUE_SLEEP |
DEQUEUE_NOCLOCK);
Regards
Gaurav
On 1/11/2019 9:47 PM, Qian Cai wrote:
On Fri, 2019-01-11 at 16:07 +0530, Kohli, Gaurav wrote:
On 1/7/2019 11:26 PM, Oleg Nesterov wrote:
pr_crit("XXX: %ld %d\n", current->state, current->o
Hi,
it don't seems to be good idea to put lock on one function and unlock in
some other function. If in future some one has to call tty_init_dev, how
he can track the unlocking as well of ldisc lock.
Regards
Gaurav
On 12/24/2018 8:13 AM, Li RongQing wrote:
There still is a race window after
On 1/7/2019 11:26 PM, Oleg Nesterov wrote:
pr_crit("XXX: %ld %d\n", current->state, current->on_rq);
Can we also add flags, this may help to know the path of problem:
pr_crit("XXX: %ld %d 0x%x\n", current->state, current->on_rq,
current->flags);
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Qualcomm India Private Limited, on b
Hi ,
Sorry for very late reminder, just wanted to know is below understanding
of code is wrong?
Regards
Gaurav
On 4/17/2018 11:59 AM, Kohli, Gaurav wrote:
On 4/17/2018 3:18 AM, Tejun Heo wrote:
On Fri, Apr 13, 2018 at 03:05:03PM +0530, Gaurav Kohli wrote:
During percpu_counter destroy
On 8/2/2018 12:04 PM, Thomas Gleixner wrote:
On Thu, 2 Aug 2018, Gaurav Kohli wrote:
Timer wheel base->must_forward_clock is indicating that
the base clock might be stale due to a long idle sleep.
The forwarding of base clock takes place in softirq of timer
of the base clock takes place in
Hi John, Thomas,
Can you please review below patch and update your comments:
Regards
Gaurav
On 7/26/2018 2:12 PM, Gaurav Kohli wrote:
While migrating timer to new base, there is a need
to update base clk by calling forward_timer_base to
avoid stale clock , but at the same time if run_timer
is
HI Greg,
Yes more patches related to this are coming,
https://lkml.org/lkml/2018/6/7/317
So i thought, if all go together then it is good.
Regards
Gaurav
On 6/21/2018 12:21 AM, Greg Kroah-Hartman wrote:
On Wed, Jun 20, 2018 at 12:10:31PM +0530, Kohli, Gaurav wrote:
Hi Greg,
As more patches
Hi Greg,
As more patches related to this are coming in 4.17, so it is better if
all go together on different branches, plz suggest.
Regards
Gaurav
On 6/18/2018 1:42 PM, Greg Kroah-Hartman wrote:
4.16-stable review patch. If anyone has any objections, please let me know.
--
HI ,
In the latest patch mentioned, k should be their instead of p:
-WARN_ON_ONCE(!wait_task_inactive(p, TASK_PARKED))
+WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED))
Regards
Gaurav
On 6/7/2018 12:29 AM, Peter Zijlstra wrote:
On Wed, Jun 06, 2018 at 03:51:16PM +0200, Oleg Nesterov wrote:
Hi,
Just for info , the patch that I have shared earlier with pi_lock
approach has been tested since last one month and no issue has been
observed,
https://lkml.org/lkml/2018/4/25/189
Can we take this if it looks good?
Regards
Gaurav
On 6/5/2018 10:05 PM, Oleg Nesterov wrote:
On 06/05, Pe
ssue.
Regards
Gaurav
On 5/7/2018 4:53 PM, Kohli, Gaurav wrote:
Corrected the formatting, Sorry for spam.
HI Peter,
We have tested with new patch and still seeing same issue, in this
dumps we don't have debug traces, but seems there still exist race
from code review , Can you p
Corrected the formatting, Sorry for spam.
HI Peter,
We have tested with new patch and still seeing same issue, in this dumps
we don't have debug traces, but seems there still exist race from code
review , Can you please check it once:
Controller Thread CPUHP
On 5/2/2018 3:43 PM, Kohli, Gaurav wrote:
On 5/2/2018 1:50 PM, Peter Zijlstra wrote:
On Wed, May 02, 2018 at 10:45:52AM +0530, Kohli, Gaurav wrote:
On 5/1/2018 6:49 PM, Peter Zijlstra wrote:
- complete(&kthread->parked), which we can do inside schedule();
this
solves the
On 5/2/2018 1:50 PM, Peter Zijlstra wrote:
On Wed, May 02, 2018 at 10:45:52AM +0530, Kohli, Gaurav wrote:
On 5/1/2018 6:49 PM, Peter Zijlstra wrote:
- complete(&kthread->parked), which we can do inside schedule(); this
solves the problem because then kthread_park() will not
On 5/1/2018 6:49 PM, Peter Zijlstra wrote:
On 5/1/2018 5:01 PM, Peter Zijlstra wrote:
Let me ponder what the best solution is, it's a bit of a mess.
So there's:
- TASK_PARKED, which we can make a special state; this solves the
problem because then wait_task_inactive() is guaranteed
On 5/1/2018 5:01 PM, Peter Zijlstra wrote:
On Tue, May 01, 2018 at 04:10:53PM +0530, Kohli, Gaurav wrote:
Yes with loop, it will reset TASK_PARKED but that is not happening in the
dumps we have seen.
But was that with or without the fixed wait-loop? I don't care about
stuff you might
On 5/1/2018 3:48 PM, Peter Zijlstra wrote:
On Tue, May 01, 2018 at 01:20:26PM +0530, Kohli, Gaurav wrote:
But In our older case, where we have seen failure below is the wake up path
and ftraces, Wakeup occured and completed before schedule call only.
So final state of CPUHP is running not
sorry for spam, Adding list
On 4/30/2018 4:47 PM, Peter Zijlstra wrote:
On Thu, Apr 26, 2018 at 09:23:25PM +0530, Kohli, Gaurav wrote:
On 4/26/2018 2:27 PM, Peter Zijlstra wrote:
On Thu, Apr 26, 2018 at 10:41:31AM +0200, Peter Zijlstra wrote:
diff --git a/kernel/kthread.c b/kernel/kthread.c
On 4/26/2018 2:27 PM, Peter Zijlstra wrote:
On Thu, Apr 26, 2018 at 10:41:31AM +0200, Peter Zijlstra wrote:
diff --git a/kernel/kthread.c b/kernel/kthread.c
index cd50e99202b0..4b6503c6a029 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -177,12 +177,13 @@ void *kthread_probe_data(struc
On 4/26/2018 1:39 AM, Peter Zijlstra wrote:
On Wed, Apr 25, 2018 at 02:03:19PM +0530, Gaurav Kohli wrote:
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index 5043e74..c5c5184 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -122,7 +122,45 @@ static int smpboot_thread_fn(void *data)
On 4/24/2018 11:56 PM, Peter Zijlstra wrote:
On Tue, Apr 24, 2018 at 02:58:25PM +0530, Gaurav Kohli wrote:
The control cpu thread which initiates hotplug calls kthread_park()
for hotplug thread and sets KTHREAD_SHOULD_PARK. After this control
thread wakes up the hotplug thread. There is a chanc
Hi ,
We can also fix below race by smpboot code as well:
@@ -109,7 +109,6 @@ static int smpboot_thread_fn(void *data)
struct smp_hotplug_thread *ht = td->ht;
while (1) {
- set_current_state(TASK_INTERRUPTIBLE);
preempt_disable();
On 4/17/2018 3:18 AM, Tejun Heo wrote:
On Fri, Apr 13, 2018 at 03:05:03PM +0530, Gaurav Kohli wrote:
During percpu_counter destroy, debug_object_free is calling
twice which may create race. So removing once instance of call
from debug_percpu_counter_deactivate.
I don't quite follow. Can you p
list.
Regards
Gaurav
On 4/13/2018 1:12 PM, Nikolay Borisov wrote:
On 13.04.2018 10:32, Kohli, Gaurav wrote:
Hi ,
I have checked below code and it seems we are calling debug_object_free
twice, ideally we should deactivate and later we
have to destroy.
1st call -> percpu_counter_dest
Hi ,
I have checked below code and it seems we are calling debug_object_free twice,
ideally we should deactivate and later we
have to destroy.
1st call -> percpu_counter_destroy->debug_percpu_counter_deactivate ->
debug_object_free
2nd call ->
debug_object_free
static bool percpu_counter_fi
On 3/9/2018 4:18 PM, Tetsuo Handa wrote:
Kohli, Gaurav wrote:
t->alloc_lock is still held when leaving find_lock_task_mm(), which means
that t->mm != NULL. But nothing prevents t from setting t->mm = NULL at
exit_mm() from do_exit() and calling exit_creds() from __put_task_struct
On 3/8/2018 2:26 AM, David Rientjes wrote:
On Wed, 7 Mar 2018, Gaurav Kohli wrote:
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6fd9773..5f4cc4b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -114,9 +114,11 @@ struct task_struct *find_lock_task_mm(struct task_struct
*p)
for_each_
Thanks Greg,
I will check the common tree, and it seems to me a new bug , will file a
bug if won't be able to
resolve from android-common tree.
Regards
Gaurav
On 3/4/2018 12:57 AM, Greg Kroah-Hartman wrote:
On Sat, Mar 03, 2018 at 08:22:35PM +0530, Kohli, Gaurav wrote:
HI ,
Is
Hi,
We have seen few instances, where init is getting blocked due to wait in below
call:
-002|schedule()
-003|schedule_timeout() -> timeout for 30 seconds
-004|tty_wait_until_sent()
-005|tty_port_close_start.part.3()
-006|tty_port_close()
-007|uart_close()
-008|tty_name(inline)
-008|tty_releas
HI ,
Is there any known issue of slab poisoning in binder_transaction variable on
kernel 4.9,
it seems owner variable of spinlock is
getting corrupted(which is last 8th byte of binder_transaction struct).
368.423462: <2> [] print_trailer+0x13c/0x214
368.428998: <2> [] check_bytes_a
On 1/6/2018 1:20 PM, Kohli, Gaurav wrote:
On 1/6/2018 2:35 AM, Alan Cox wrote:
On Sat, 6 Jan 2018 01:54:36 +0530
"Kohli, Gaurav" wrote:
Hi Alan,
Sorry correcting the typo here:
+retval = tty_ldisc_lock(tty, 5 * HZ);
+if (retval)
+ goto err_release_lock;
tty->por
On 1/16/2018 12:50 PM, Alexey Dobriyan wrote:
On Tue, Jan 16, 2018 at 11:06:47AM +0530, Kohli, Gaurav wrote:
On 1/10/2018 10:50 AM, Alexey Dobriyan wrote:
We are seeing crash in do_task_stat while accessing stack pointer, It
seems same task has already completed do_exit call.
So it seems a
On 1/10/2018 10:50 AM, Alexey Dobriyan wrote:
We are seeing crash in do_task_stat while accessing stack pointer, It
seems same task has already completed do_exit call.
So it seems a race between them:
Please, post exact kernel version and struct task_struct::usage if you
still have that kernel
On 1/15/2018 4:32 PM, John Ogness wrote:
Hello Gaurav.
On 2018-01-09, Kohli, Gaurav wrote:
We are seeing crash in do_task_stat while accessing stack pointer, It
seems same task has already completed do_exit call.
So it seems a race between them:
Below is the crash trace:
49750.534377
eip = KSTK_EIP(task);
esp = KSTK_ESP(task);
}
Regards
Gaurav
On 1/9/2018 7:03 PM, Kohli, Gaurav wrote:
HI ,
We are seeing crash in do_task_stat while accessing stack pointer, It
seems same task has already completed do_exit call.
So it seems a race between them:
HI ,
We are seeing crash in do_task_stat while accessing stack pointer, It
seems same task has already completed do_exit call.
So it seems a race between them:
Below is the crash trace:
49750.534377] Kernel BUG at ff8e7a4c53a8 [verbose debug info
unavailable]
[49750.534394] task: ffe
On 1/6/2018 2:35 AM, Alan Cox wrote:
On Sat, 6 Jan 2018 01:54:36 +0530
"Kohli, Gaurav" wrote:
Hi Alan,
Sorry correcting the typo here:
+retval = tty_ldisc_lock(tty, 5 * HZ);
+if (retval)
+ goto err_release_lock;
tty->port->itty = tty;
/*
* Structures all instal
HI Alan,
Sorry correcting the typo here:
On 1/6/2018 1:44 AM, Kohli, Gaurav wrote:
Hi Alan,
On 1/5/2018 7:45 PM, Alan Cox wrote:
But in above case , there we can hit another race, if we have a
sequence
like this
tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will
i
elease_lock;
+tty_unlock(tty);
+release_tty(tty, idx);
+tty_ldisc_unlock(tty);
+return ERR_PTR(retval);
On 1/6/2018 1:44 AM, Kohli, Gaurav wrote:
Hi Alan,
On 1/5/2018 7:45 PM, Alan Cox wrote:
But in above case , there we can hit another race, if we have a
sequence
like this
tty_in
Hi Alan,
On 1/5/2018 7:45 PM, Alan Cox wrote:
But in above case , there we can hit another race, if we have a sequence
like this
tty_init_dev->alloc_tty_struct -> tty_ldisc_init -> this will initialize
ldisc ,
but at this moment disc_data is still NULL
And if flush_to_ldisc comes in between, i
On 1/5/2018 7:06 PM, Alan Cox wrote:
On Fri, 5 Jan 2018 13:15:45 +0530
"Kohli, Gaurav" wrote:
Hi Alan,
Can you make that code available otherwise it's impossible to see
what the problem might be.
https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/s
Hi Alan,
Can you make that code available otherwise it's impossible to see
what the problem might be.
https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/serial?h=msm-4.9
As discussed , there not seems a problem as we are getting print
request even when port seems to c
Which tty driver ? serial/msm_serial.c ?
We are using our internal driver, msm_geni_serial.c
Ok no what I need to see is a trace of what each CPU is doing at the
point you detect the problem. That way we can see what the path that
races is.
Below is stack trace running by init in our cas
Hi ,
We have seen lot of crashes in 4.9 during boot in
n_tty_receive_buf_common, when tty->disc_data
becomes NULL, Below is the call stack for same
29.710969] PC is at n_tty_receive_buf_common+0x68/0xa3c
[ 29.716425] LR is at n_tty_receive_buf_common+0x58/0xa3c
[ 29.721882] pc : [] lr : []
Hi ,
Can we profile driver specific notifier callback from Linux notifier.
Sometimes we need to debug which callback is taking more time or where
it is stuck.
If kernel/notifier.c provide generic mechanism to profile callbacks that
will
save profiling individual callbacks.
--
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