Now there are several places to use __vmalloc with GFP_ATOMIC, GFP_NOIO, GFP_NOFS but unfortunately __vmalloc calls map_vm_area which calls alloc_pages with GFP_KERNEL to allocate page tables. It means it's possible to happen deadlock. I don't know why it doesn't have reported until now. Firstly, I tried passing gfp_t to lower functions to support __vmalloc with such flags but other mm guys don't want and decided that all of caller should be fixed. http://marc.info/?l=linux-kernel&m=133517143616544&w=2 To begin with, let's listen other's opinion whether they can fix it by other approach without calling __vmalloc with such flags. So this patch adds warning in __vmalloc_node_range to detect it and to be fixed hopely. __vmalloc_node_range isn't random chocie because all caller which has gfp_mask of map_vm_area use it through __vmalloc_area_node. And __vmalloc_area_node is current static function and is called by only __vmalloc_node_range. So warning in __vmalloc_node_range would cover all vmalloc functions which have gfp_t argument. I Cced related maintainers. If I miss someone, please Cced them. * Changelog * Replace WARN_ON with WARN_ON_ONCE - by Andrew Morton, Nick Piggin. Cc: Neil Brown <neilb@xxxxxxx> Cc: Artem Bityutskiy <dedekind1@xxxxxxxxx> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> Cc: "Theodore Ts'o" <tytso@xxxxxxx> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx> Cc: Steven Whitehouse <swhiteho@xxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: James Morris <jmorris@xxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Sage Weil <sage@xxxxxxxxxxxx> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> --- mm/vmalloc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index c28b0b9..def5943 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1648,6 +1648,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, void *addr; unsigned long real_size = size; + WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT) || + !(gfp_mask & __GFP_IO) || + !(gfp_mask & __GFP_FS)); + size = PAGE_ALIGN(size); if (!size || (size >> PAGE_SHIFT) > totalram_pages) goto fail; -- 1.7.9.5 -- 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>