On Fri, 27 Mar 2015 13:39:38 +0200 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
> set_recommended_min_free_kbytes() adjusts zone water marks to be suitable
> for khugepaged. We avoid doing this if khugepaged is disabled, but don't
> catch the case when khugepaged is failed to start.
>
> Let's address this by checking khugepaged_thread instead of
> khugepaged_enabled() in set_recommended_min_free_kbytes().
> It's NULL if the kernel thread is stopped or failed to start.
>
hm, why didn't khugepaged start up? Is this a theoretical
by-code-inspection thing or has the problem been observed in real life?
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -110,7 +110,8 @@ static int set_recommended_min_free_kbytes(void)
> int nr_zones = 0;
> unsigned long recommended_min;
>
> - if (!khugepaged_enabled())
> + /* khugepaged thread has stopped to failed to start */
> + if (!khugepaged_thread)
> return 0;
>
> for_each_populated_zone(zone)
Fair enough, but take a look at start_khugepaged():
: static int start_khugepaged(void)
: {
: int err = 0;
: if (khugepaged_enabled()) {
: if (!khugepaged_thread)
: khugepaged_thread = kthread_run(khugepaged, NULL,
: "khugepaged");
: if (unlikely(IS_ERR(khugepaged_thread))) {
: pr_err("khugepaged: kthread_run(khugepaged) failed\n");
: err = PTR_ERR(khugepaged_thread);
: khugepaged_thread = NULL;
-->> stop here
: }
:
: if (!list_empty(&khugepaged_scan.mm_head))
: wake_up_interruptible(&khugepaged_wait);
:
: set_recommended_min_free_kbytes();
: } else if (khugepaged_thread) {
: kthread_stop(khugepaged_thread);
: khugepaged_thread = NULL;
: }
:
: return err;
: }
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>