From: Michal Hocko <mhocko@xxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Neil Brown <neilb@xxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Uladzislau Rezki <urezki@xxxxxxxxx> Cc: Ilya Dryomov <idryomov@xxxxxxxxx> Cc: Jeff Layton <jlayton@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/mm/vmalloc.c~mm-vmalloc-be-more-explicit-about-supported-gfp-flags +++ a/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 */ _
