On 07/18/2016 10:00 AM, Xishi Qiu wrote:
On 2016/7/18 13:51, Joonsoo Kim wrote:
On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote:
alloc_migrate_target() is called from migrate_pages(), and the page
is always from user space, so we can add __GFP_HIGHMEM directly.
No, all migratable pages are not from user space. For example,
blockdev file cache has __GFP_MOVABLE and migratable but it has no
__GFP_HIGHMEM and __GFP_USER.
Hi Joonsoo,
So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;"
is not correct?
It's not incorrect. GFP_USER just specifies some reclaim flags, and may
perhaps restrict allocation through __GFP_HARDWALL, where the original
page could have been allocated without the restriction. But it doesn't
put the place in an unexpected address range, as placing a non-highmem
page into highmem could. __GFP_MOVABLE then just controls a heuristic
for placement within a zone.
And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE.
Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing
mem-hotplug?
I don't understand the question here, can you rephrase with more detail?
Thanks.
Thanks,
Xishi Qiu
Thanks.
.
--
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/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>