From: Michal Hocko Date: Fri, 5 Nov 2021 20:39:50 +0000 (-0700) Subject: mm/vmalloc: be more explicit about supported gfp flags X-Git-Tag: v5.16-rc1~106^2~163 X-Git-Url: https://repo.jachan.dev/linux.git/commitdiff_plain/b7d90e7a5ea8 mm/vmalloc: be more explicit about supported gfp flags The core of the vmalloc allocator __vmalloc_area_node doesn't say anything about gfp mask argument. Not all gfp flags are supported though. Be more explicit about constraints. Link: https://lkml.kernel.org/r/20211020082545.4830-1-mhocko@kernel.org Signed-off-by: Michal Hocko Cc: Dave Chinner Cc: Neil Brown Cc: Christoph Hellwig Cc: Uladzislau Rezki Cc: Ilya Dryomov Cc: Jeff Layton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 75fa100f5424..c56720136c45 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2983,8 +2983,16 @@ fail: * @caller: caller's return address * * Allocate enough pages to cover @size from the page level - * allocator with @gfp_mask flags. Map them into contiguous - * kernel virtual space, using a pagetable protection of @prot. + * allocator with @gfp_mask flags. Please note that the full set of gfp + * flags are not supported. GFP_KERNEL would be a preferred allocation mode + * but GFP_NOFS and GFP_NOIO are supported as well. Zone modifiers are not + * supported. From the reclaim modifiers__GFP_DIRECT_RECLAIM is required (aka + * GFP_NOWAIT is not supported) and only __GFP_NOFAIL is supported (aka + * __GFP_NORETRY and __GFP_RETRY_MAYFAIL are not supported). + * __GFP_NOWARN can be used to suppress error messages about failures. + * + * Map them into contiguous kernel virtual space, using a pagetable + * protection of @prot. * * Return: the address of the area or %NULL on failure */