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Subject[PATCH 05/11] zsmalloc: switch from alloc_vm_area to get_vm_area
Date
Just manually pre-fault the PTEs using apply_to_page_range.

Co-developed-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
mm/zsmalloc.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c36fdff9a37131..918c7b019b3d78 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1122,10 +1122,16 @@ static inline int __zs_cpu_up(struct mapping_area *area)
*/
if (area->vm)
return 0;
- area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
+ area->vm = get_vm_area(PAGE_SIZE * 2, 0);
if (!area->vm)
return -ENOMEM;
- return 0;
+
+ /*
+ * Populate ptes in advance to avoid pte allocation with GFP_KERNEL
+ * in non-preemtible context of zs_map_object.
+ */
+ return apply_to_page_range(&init_mm, (unsigned long)area->vm->addr,
+ PAGE_SIZE * 2, NULL, NULL);
}

static inline void __zs_cpu_down(struct mapping_area *area)
--
2.28.0
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