Re: [PATCH v2 3/4] mm: Introduce page_needs_cow_for_dma() for deciding whether cow
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: 2021-02-04 17:56:56
Also in:
lkml
On Thu, Feb 4, 2021 at 6:50 AM Peter Xu [off-list ref] wrote:
quoted hunk ↗ jump to hunk
--- a/include/linux/mm.h +++ b/include/linux/mm.h@@ -1291,6 +1291,27 @@ static inline bool page_maybe_dma_pinned(struct page *page) GUP_PIN_COUNTING_BIAS; } +static inline bool is_cow_mapping(vm_flags_t flags) +{ + return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; +}
Oh, and I just realized: moving this to <linux/mm.h> means that this
patch could/should also get rid of
- manual copy of this in mm/hugetlb.c:
cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
- private #define for the same thing in fs/proc/task_mmu.c
#define is_cow_mapping(flags) (((flags) & (VM_SHARED |
VM_MAYWRITE)) == VM_MAYWRITE)
- manual copy in drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c:
bool is_cow_mapping =
(vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
I guess it could be a later cleanup patch too, but maybe best done in
this series just to not forget about it.
Linus