From: Christoph Hellwig <hch@xxxxxx> Subject: zsmalloc: switch from alloc_vm_area to get_vm_area Just manually pre-fault the PTEs using apply_to_page_range. Link: https://lkml.kernel.org/r/20201002122204.1534411-6-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Co-developed-by: Minchan Kim <minchan@xxxxxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Matthew Auld <matthew.auld@xxxxxxxxx> Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Cc: Nitin Gupta <ngupta@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/zsmalloc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/mm/zsmalloc.c~zsmalloc-switch-from-alloc_vm_area-to-get_vm_area +++ a/mm/zsmalloc.c @@ -1122,10 +1122,16 @@ static inline int __zs_cpu_up(struct map */ 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) _
