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 <mhocko@suse.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2021-11-05 13:39:50 -07:00 committed by Linus Torvalds
parent 3252b1d830
commit b7d90e7a5e

View File

@ -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
*/