With defrag mode enabled per default, huge page allocations pass __GFP_WAIT and may drop compaction into sync-mode where they wait for pages under writeback. I observe applications hang for several minutes(!) when they fault in huge pages and compaction starts to wait on in-"flight" USB stick IO. This patch disables defrag mode for page fault allocations unless the VMA is madvised explicitely. Khugepaged will continue to allocate with __GFP_WAIT per default, but stalls are not a problem of application responsiveness there. Signed-off-by: Johannes Weiner <jweiner@xxxxxxxxxx> --- mm/huge_memory.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 81532f2..8c8ff29 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -35,7 +35,7 @@ unsigned long transparent_hugepage_flags __read_mostly = #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| #endif - (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| + (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); /* default scan 8*512 pte (or vmas) every 30 second */ -- 1.7.6 -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>