Robin Holt wrote: > On Fri, May 18, 2007 at 09:50:03AM +0200, Andrea Righi wrote: >> Rik van Riel wrote: >>> Andrea Righi wrote: >>>> I'm looking for a way to keep track of the processes that fail to >>>> allocate new >>>> virtual memory. What do you think about the following approach >>>> (untested)? >>> Looks like an easy way for users to spam syslogd over and >>> over and over again. >>> >>> At the very least, shouldn't this be dependant on print_fatal_signals? >>> >> Anyway, with print-fatal-signals enabled a user could spam syslogd too, >> simply >> with a (char *)0 = 0 program, but we could always identify the spam attempts >> logging the process uid... >> >> In any case, I agree, it should depend on that patch... >> >> What about adding a simple msleep_interruptible(SOME_MSECS) at the end of >> log_vm_enomem() or, at least, a might_sleep() to limit the potential >> spam/second >> rate? > > An msleep will slow down this process, but do nothing about slowing > down the amount of logging. Simply fork a few more processes and all > you are doing with msleep is polluting the pid space. >
Very true. > What about a throttling similar to what ia64 does for floating point > assist faults (handle_fpu_swa()). There is a thread flag to not log > the events at all. It is rate throttled globally, but uses per cpu > variables for early exits. This algorithm scaled well to a thousand > cpus. Actually using printk_ratelimit() should be enough... BTW print_fatal_signals() should use it too. -Andrea --- Signed-off-by: Andrea Righi <[EMAIL PROTECTED]> diff -urpN linux-2.6.21/mm/mmap.c linux-2.6.21-vm-log-enomem/mm/mmap.c --- linux-2.6.21/mm/mmap.c 2007-04-26 05:08:32.000000000 +0200 +++ linux-2.6.21-vm-log-enomem/mm/mmap.c 2007-05-18 17:17:32.000000000 +0200 @@ -77,6 +77,29 @@ int sysctl_max_map_count __read_mostly = atomic_t vm_committed_space = ATOMIC_INIT(0); /* + * 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_INFO + "out of virtual memory for process %d (%s): total_vm=%lu, uid=%d\n", + current->pid, current->comm, 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 * succeed and -ENOMEM implies there is not. @@ -175,6 +198,7 @@ int __vm_enough_memory(long pages, int c return 0; error: vm_unacct_memory(pages); + log_vm_enomem(); return -ENOMEM; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/