On 2015/06/04 22:02, Xishi Qiu wrote:
This patch introduces a new gfp flag called "__GFP_MIRROR", it is used to
allocate mirrored pages through buddy system.
Signed-off-by: Xishi Qiu <qiuxi...@huawei.com>
In Tony's original proposal, the motivation was to mirror all kernel memory.
Is the purpose of this patch making mirrored range available for user space ?
But, hmm... I don't think adding a new GFP flag is a good idea. It adds many
conditional jumps.
How about using GFP_KERNEL for user memory if the user wants mirrored memory
with mirroring
all kernel memory?
Thanks,
-Kame
---
include/linux/gfp.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 15928f0..89d0091 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -35,6 +35,7 @@ struct vm_area_struct;
#define ___GFP_NO_KSWAPD 0x400000u
#define ___GFP_OTHER_NODE 0x800000u
#define ___GFP_WRITE 0x1000000u
+#define ___GFP_MIRROR 0x2000000u
/* If the above are modified, __GFP_BITS_SHIFT may need updating */
/*
@@ -95,13 +96,15 @@ struct vm_area_struct;
#define __GFP_OTHER_NODE ((__force gfp_t)___GFP_OTHER_NODE) /* On behalf of
other node */
#define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) /* Allocator intends to
dirty page */
+#define __GFP_MIRROR ((__force gfp_t)___GFP_MIRROR) /* Allocate mirrored
memory */
+
/*
* This may seem redundant, but it's a way of annotating false positives vs.
* allocations that simply cannot be supported (e.g. page tables).
*/
#define __GFP_NOTRACK_FALSE_POSITIVE (__GFP_NOTRACK)
-#define __GFP_BITS_SHIFT 25 /* Room for N __GFP_FOO bits */
+#define __GFP_BITS_SHIFT 26 /* Room for N __GFP_FOO bits */
#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
/* This equals 0, but use constants in case they ever change */
--
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