RFC get rid of GFP_ZONE_TABLE/BAD
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Cover letter [RFC PATCH v3 0/9] get rid of GFP_ZONE_TABLE/BAD
From: Huaisheng Ye <[email protected]>
Changes since v2: [2]
* According to Christoph's suggestion, rebase patches to current mainline from v4.16.
* Follow the advice of Matthew, create macros like GFP_NORMAL and GFP_NORMAL_UNMOVABLE to clear bottom 3 and 4 bits of GFP bitmask.
* Delete some patches because of kernel updating.
[2]: https://marc.info/?l=linux-mm&m=152691610014027&w=2
Tested by Lenovo Thinksystem server.
Initmem setup node 0 [mem 0x0000000000001000-0x000000043fffffff]
[ 0.000000] On node 0 totalpages: 4111666 [ 0.000000] DMA zone: 64 pages used for memmap [ 0.000000] DMA zone: 23 pages reserved [ 0.000000] DMA zone: 3999 pages, LIFO batch:0 [ 0.000000] mminit::memmap_init Initialising map node 0 zone 0 pfns 1 -> 4096 [ 0.000000] DMA32 zone: 10935 pages used for memmap [ 0.000000] DMA32 zone: 699795 pages, LIFO batch:31 [ 0.000000] mminit::memmap_init Initialising map node 0 zone 1 pfns 4096 -> 1048576 [ 0.000000] Normal zone: 53248 pages used for memmap [ 0.000000] Normal zone: 3407872 pages, LIFO batch:31 [ 0.000000] mminit::memmap_init Initialising map node 0 zone 2 pfns 1048576 -> 4456448 [ 0.000000] mminit::memmap_init Initialising map node 0 zone 3 pfns 1 -> 4456448 [ 0.000000] Initmem setup node 1 [mem 0x0000002380000000-0x000000277fffffff] [ 0.000000] On node 1 totalpages: 4194304 [ 0.000000] Normal zone: 65536 pages used for memmap [ 0.000000] Normal zone: 4194304 pages, LIFO batch:31 [ 0.000000] mminit::memmap_init Initialising map node 1 zone 2 pfns 37224448 -> 41418752 [ 0.000000] mminit::memmap_init Initialising map node 1 zone 3 pfns 37224448 -> 41418752 ... [ 0.000000] mminit::zonelist general 0:DMA = 0:DMA [ 0.000000] mminit::zonelist general 0:DMA32 = 0:DMA32 0:DMA [ 0.000000] mminit::zonelist general 0:Normal = 0:Normal 0:DMA32 0:DMA 1:Normal [ 0.000000] mminit::zonelist thisnode 0:DMA = 0:DMA [ 0.000000] mminit::zonelist thisnode 0:DMA32 = 0:DMA32 0:DMA [ 0.000000] mminit::zonelist thisnode 0:Normal = 0:Normal 0:DMA32 0:DMA [ 0.000000] mminit::zonelist general 1:Normal = 1:Normal 0:Normal 0:DMA32 0:DMA [ 0.000000] mminit::zonelist thisnode 1:Normal = 1:Normal [ 0.000000] Built 2 zonelists, mobility grouping on. Total pages: 8176164 [ 0.000000] Policy zone: Normal [ 0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz-4.17.0-rc6-gfp09+
root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root rd.lvm.lv=fedora/swap debug LANG=en_US.UTF-8 mminit_loglevel=4 console=tty0 console=ttyS0,115200n8 memblock=debug earlyprintk=serial,0x3f8,115200
---
Replace GFP_ZONE_TABLE and GFP_ZONE_BAD with encoded zone number.
Delete ___GFP_DMA, ___GFP_HIGHMEM and ___GFP_DMA32 from GFP bitmasks, the bottom three bits of GFP mask is reserved for storing encoded zone number.
The encoding method is XOR. Get zone number from enum zone_type, then encode the number with ZONE_NORMAL by XOR operation. The goal is to make sure ZONE_NORMAL can be encoded to zero. So, the compatibility can be guaranteed, such as GFP_KERNEL and GFP_ATOMIC can be used as before.
Reserve __GFP_MOVABLE in bit 3, so that it can continue to be used as a flag. Same as before, __GFP_MOVABLE respresents movable migrate type for ZONE_DMA, ZONE_DMA32, and ZONE_NORMAL. But when it is enabled with __GFP_HIGHMEM, ZONE_MOVABLE shall be returned instead of ZONE_HIGHMEM. __GFP_ZONE_MOVABLE is created to realize it.
With this patch, just enabling __GFP_MOVABLE and __GFP_HIGHMEM is not enough to get ZONE_MOVABLE from gfp_zone. All callers should use GFP_HIGHUSER_MOVABLE or __GFP_ZONE_MOVABLE directly to achieve that.
Decode zone number directly from bottom three bits of flags in gfp_zone. The theory of encoding and decoding is,
A ^ B ^ B = A
Changes since v1:[1]
* Create __GFP_ZONE_MOVABLE and modify GFP_HIGHUSER_MOVABLE to help callers to get ZONE_MOVABLE. Try to create __GFP_ZONE_MASK to mask lowest 3 bits of GFP bitmasks.
* Modify some callers' gfp flag to update usage of address zone modifiers.
* Modify inline function gfp_zone to get better performance according to Matthew's suggestion.
[1]: https://marc.info/?l=linux-mm&m=152596791931266&w=2
---
Huaisheng Ye (9):
include/linux/gfp.h: get rid of GFP_ZONE_TABLE/BAD include/linux/dma-mapping: update usage of zone modifiers drivers/xen/swiotlb-xen: update usage of zone modifiers fs/btrfs/extent_io: update usage of zone modifiers drivers/block/zram/zram_drv: update usage of zone modifiers mm/vmpressure: update usage of zone modifiers mm/zsmalloc: update usage of zone modifiers include/linux/highmem.h: update usage of movableflags arch/x86/include/asm/page.h: update usage of movableflags
arch/x86/include/asm/page.h | 3 +- drivers/block/zram/zram_drv.c | 6 +-- drivers/xen/swiotlb-xen.c | 2 +- fs/btrfs/extent_io.c | 2 +- include/linux/dma-mapping.h | 2 +- include/linux/gfp.h | 107 ++++++++---------------------------------- include/linux/highmem.h | 4 +- mm/vmpressure.c | 2 +- mm/zsmalloc.c | 4 +- 9 files changed, 32 insertions(+), 100 deletions(-)
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