[PATCH 2/2] log out-of-virtual-memory events (was: [RFC] log out-of-virtual-memory events)

[PATCH 2/2] log out-of-virtual-memory events (was: [RFC] log out-of-virtual-memory events)

[Andrea Righi]

Bernd Eckenfels wrote:
> In article <464DCC52.7090403@users.sourceforge.net> you wrote:
>> +       printk(KERN_INFO
>> +              "out of virtual memory for process %d (%s): total_vm=%lu, uid=%d\n",
>> +               current->pid, current->comm, total_vm, current->uid);
> 
> And align this one with the print_fatal layout:
> 
>        printk(KERN_WARNING
>               "%s/%d process cannot request more virtual memory: total_vm=%lu, uid=%d\n",
>                current->comm, current->pid, total_vm, current->uid);
> 

Depends on print_fatal_signals patch.

---

Print informations about userspace processes that fail to allocate new virtual
memory.

Signed-off-by: Andrea Righi <a.righi@cineca.it>

diff -urpN linux-2.6.22-rc1-mm1/mm/mmap.c linux-2.6.22-rc1-mm1-vm-log-enomem/mm/mmap.c
--- linux-2.6.22-rc1-mm1/mm/mmap.c	2007-05-19 11:25:24.000000000 +0200
+++ linux-2.6.22-rc1-mm1-vm-log-enomem/mm/mmap.c	2007-05-19 11:55:05.000000000 +0200
@@ -77,6 +77,31 @@ int sysctl_overcommit_ratio = 50;	/* def
 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
 atomic_t vm_committed_space = ATOMIC_INIT(0);
 
+extern int print_fatal_signals;
+
+/*
+ * Print current process informations when it fails to allocate new virtual
+ * memory.
+ */
+static inline void log_vm_enomem(void)
+{
+	unsigned long total_vm = 0;
+	struct mm_struct *mm;
+
+	if (unlikely(!printk_ratelimit()))
+		return;
+
+	task_lock(current);
+	mm = current->mm;
+	if (mm)
+		total_vm = mm->total_vm;
+	task_unlock(current);
+
+	printk(KERN_WARNING
+	       "%s/%d process cannot request more virtual memory: total_vm=%lu, uid=%d\n",
+	       current->comm, current->pid, total_vm, current->uid);
+}
+
 /*
  * Check that a process has enough memory to allocate a new virtual
  * mapping. 0 means there is enough memory for the allocation to
@@ -177,6 +202,9 @@ int __vm_enough_memory(long pages, int c
 error:
 	vm_unacct_memory(pages);
 
+	if (print_fatal_signals)
+		log_vm_enomem();
+
 	return -ENOMEM;
 } 

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Re: [PATCH 2/2] log out-of-virtual-memory events (was: [RFC] log out-of-virtual-memory events)

[Andrew Morton]

On Sat, 19 May 2007 12:34:01 +0200 (MEST) Andrea Righi <righiandr@users.sourceforge.net> wrote:

> Print informations about userspace processes that fail to allocate new virtual
> memory.

Why is this useful?

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Re: [PATCH 2/2] log out-of-virtual-memory events

[Andrea Righi]

Andrew Morton wrote:
> On Sat, 19 May 2007 12:34:01 +0200 (MEST) Andrea Righi <righiandr@users.sourceforge.net> wrote:
> 
>> Print informations about userspace processes that fail to allocate new virtual
>> memory.
> 
> Why is this useful?
> 

Well... in strict overcommit mode (overcommit_memory=2) this is the only way to
track down problems of the (bad-designed) user applications that exit when they
receive a -ENOMEM without logging anything... and, anyway, it could be an
additional aid in figuring out what is going wrong on inside a system. BTW, I
don't think it should be enabled by default, so this is the reason why it should
depend on print_fatal_signals patch.

-Andrea

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