Messages in this thread Patch in this message |  | | | From | Minchan Kim <> | | Subject | [PATCH] vmalloc: add warning in __vmalloc | | Date | Wed, 2 May 2012 13:28:09 +0900 |
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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@suse.de> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: James Morris <jmorris@namei.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Sage Weil <sage@newdream.net> Signed-off-by: Minchan Kim <minchan@kernel.org> --- 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
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