Josip, give this debugging patch a try. It is against 2.6.23.1
but it should apply to most recent kernels.
It should give you debugging messages in the kernel log that
start with "FUTEX_BUG" if the debugging code triggers.
Please post just a few samples of whatever it spits out.
Thanks!
diff --git a/kernel/futex.c b/kernel/futex.c
index fcc94e7..6da8b3c 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1874,6 +1874,25 @@ err_unlock:
return ret;
}
+static void log_futex_bug(u32 __user *uaddr, struct task_struct *curr, int pi)
+{
+ struct mm_struct *mm = curr->mm;
+ struct vm_area_struct *vma;
+ unsigned long addr;
+
+ printk(KERN_ERR "FUTEX_BUG: Looping too much in futex death\n");
+ printk(KERN_ERR "FUTEX_BUG: uaddr[%p] task[%s:%d] pi(%d)\n",
+ uaddr, curr->comm, curr->pid, pi);
+
+ addr = (unsigned long) uaddr;
+ vma = find_vma(mm, addr);
+ if (vma)
+ printk(KERN_ERR "FUTEX_BUG: VMA start[%lx] end[%lx] flags[%lx]\n",
+ vma->vm_start,
+ vma->vm_end,
+ vma->vm_flags);
+}
+
/*
* Process a futex-list entry, check whether it's owned by the
* dying task, and do notification if so:
@@ -1881,6 +1900,7 @@ err_unlock:
int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi)
{
u32 uval, nval, mval;
+ int limit = 0;
retry:
if (get_user(uval, uaddr))
@@ -1903,8 +1923,12 @@ retry:
if (nval == -EFAULT)
return -1;
- if (nval != uval)
- goto retry;
+ if (nval != uval) {
+ if (++limit < 100)
+ goto retry;
+ log_futex_bug(uaddr, curr, pi);
+ put_user(mval, uaddr);
+ }
/*
* Wake robust non-PI futexes here. The wakeup of
-
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