PR_INFO DRUCK IN __POLLWAKE KERNEL PANIC

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Expand view Topic review: PR_INFO DRUCK IN __POLLWAKE KERNEL PANIC

by Anonymous » 31 Aug 2025, 11:18

Ich habe den folgenden Code, um zu verfolgen, welcher Prozess aufweckt, welcher Prozess in __pollwake < /p>
aufweckt.

Code: Select all

linux kernel 6.6.6x
/fs/select.c:

static int __pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
{
struct poll_wqueues *pwq = wait->private;
DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);

/*
* Although this function is called under waitqueue lock, LOCK
* doesn't imply write barrier and the users expect write
* barrier semantics on wakeup functions.  The following
* smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
* and is paired with smp_store_mb() in poll_schedule_timeout.
*/
smp_wmb();
pwq->triggered = 1;

/*
* Perform the default wake up operation using a dummy
* waitqueue.
*
* TODO: This is hacky but there currently is no interface to
* pass in @sync.  @sync is scheduled to be removed and once
* that happens, wake_up_process() can be used directly.
*/

if (wait->private && (wait->func == pollwake) && (pwq->polling_task) && strstr(pwq->polling_task->comm, "process1") != 0) {
pwqLWB = pwq;
pr_info("LWB %s:%d__pollwake: waking task current: %s (pid %d)\n", __func__, __LINE__, current->pid, current->comm);
WARN_ON(!pwq || !pwq->polling_task); pr_info("LWB DONE %s \n", pwq->polling_task->comm); polling_task->comm,
//    pwq->polling_task->pid,
//    pwq->error);
}

int rtn = default_wake_function(&dummy_wait, mode, sync, key);

if (wait->private && (wait->func == pollwake) && (pwq->polling_task) && strstr(pwq->polling_task->comm, "process1") != 0) {
pr_info("LWB %s:%d__pollwake: waking task current: %s (pid %d)\n", __func__, __LINE__,
current->pid, current->comm);
WARN_ON(!pwq || !pwq->polling_task); pr_info("LWB DONE %s\n", pwq->polling_task->comm);
//pr_info("LWB %s:%d__pollwake DONE: waking task poll_task: %s (pid %d) error:%d\n", __func__, __LINE__,
//    pwq->polling_task->comm,
//    pwq->polling_task->pid,
//    pwq->error);
}

return rtn;
}

< /code>
Und es stürzt hier ab:
pr_info("LWB DONE %s \n", pwq->polling_task->comm);

Hier ist die Absturzspur:

Code: Select all

pstate: 000000c5 (nzcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : string_nocheck+0x3c/0x70
lr : string+0x54/0x68
sp : ffff800082cc38a0
x29: ffff800082cc38a0 x28: ffff800082cc3a65 x27: ffff800080e8e126
x26: ffff800080e8e126 x25: 0000000000000020 x24: 0000000000000008
x23: 00000000ffffffe0 x22: ffff800080ca2ff8 x21: ffff0a00ffffff04
x20: 0000000000001083 x19: ffff800082cc3a38 x18: 00000000fffffffc
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
x14: ffffffffffffffff x13: ffff800082cc3a38 x12: ffff800082cc3a41
x11: 0000000000000000 x10: ffff800082cc3c10 x9 : 00000000fffffffe
x8 : ffff800082cc3a38 x7 : 000000000000000a x6 : 0000000000000002
x5 : 0000000000000002 x4 : 0000000000000000 x3 : ffff0a00ffffff04
x2 : 0000000000001083 x1 : ffff800082cc3a38 x0 : ffff800082cc3a65
Call trace:
string_nocheck+0x3c/0x70
string+0x54/0x68
vsnprintf+0x178/0x738
vprintk_store+0xd8/0x428
vprintk_emit+0x80/0x2b8
vprintk_default+0x3c/0x50
vprintk+0x94/0x100
_printk+0x50/0x60
pollwake+0x180/0x1c0
__wake_up_common+0x9c/0x190
__wake_up_locked_key+0x24/0x38
eventfd_write+0xb0/0x1b8
vfs_write+0xe0/0x458
ksys_write+0x5c/0xe0
__arm64_sys_write+0x20/0x30
el0_svc_common.constprop.0+0x60/0x138
do_el0_svc+0x20/0x30
el0_svc+0x24/0x98
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x14c/0x150
< /code>
Was ich Problemen habestrstr(pwq->polling_task->comm, "process1")
und es stürzte nicht ab und es stürzte vor, wenn ich die Zeichenfolge ausdrucken ...
Kann jemand bitte erklären, was mir fehlt?

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