On Fri, Nov 18, 2011 at 3:16 PM, John Kacur <jkacur@xxxxxxxxxx> wrote: > On Fri, Nov 18, 2011 at 3:04 PM, Hillf Danton <dhillf@xxxxxxxxx> wrote: >> In the error path that we fail to allocate new huge page, before try again, we >> have to check race since page_table_lock is re-acquired. >> >> If racing, our job is done. >> >> Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx> >> --- >> >> --- a/mm/hugetlb.c Fri Nov 18 21:38:30 2011 >> +++ b/mm/hugetlb.c Fri Nov 18 21:48:15 2011 >> @@ -2407,7 +2407,14 @@ retry_avoidcopy: >> BUG_ON(page_count(old_page) != 1); >> BUG_ON(huge_pte_none(pte)); >> spin_lock(&mm->page_table_lock); >> - goto retry_avoidcopy; >> + ptep = huge_pte_offset(mm, address & huge_page_mask(h)); >> + if (likely(pte_same(huge_ptep_get(ptep), pte))) >> + goto retry_avoidcopy; >> + /* >> + * race occurs while re-acquiring page_table_lock, and >> + * our job is done. >> + */ >> + return 0; >> } >> WARN_ON_ONCE(1); >> } > > > I'm not sure about the veracity of the race condition, but you better > do spin_unlock before you return. > Ugh, sorry for the noise, I see that's not how it works here. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href