| Message ID | 20230111215906.2645056-1-pasha.tatashin@soleen.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/page_ext: Do not allocate space for page_ext->flags if not needed | expand |
Hi Pasha,
I love your patch! Yet something to improve:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Pasha-Tatashin/mm-page_ext-Do-not-allocate-space-for-page_ext-flags-if-not-needed/20230112-055942
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20230111215906.2645056-1-pasha.tatashin%40soleen.com
patch subject: [PATCH] mm/page_ext: Do not allocate space for page_ext->flags if not needed
config: hexagon-randconfig-r012-20230110
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 8d9828ef5aa9688500657d36cd2aefbe12bbd162)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/f195fe7b408dd821eef3d052e8ebd50cccb3df51
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Pasha-Tatashin/mm-page_ext-Do-not-allocate-space-for-page_ext-flags-if-not-needed/20230112-055942
git checkout f195fe7b408dd821eef3d052e8ebd50cccb3df51
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
In file included from mm/page_owner.c:6:
In file included from include/linux/memblock.h:13:
In file included from arch/hexagon/include/asm/dma.h:9:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __raw_readb(PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
#define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
^
In file included from mm/page_owner.c:6:
In file included from include/linux/memblock.h:13:
In file included from arch/hexagon/include/asm/dma.h:9:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
#define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
^
In file included from mm/page_owner.c:6:
In file included from include/linux/memblock.h:13:
In file included from arch/hexagon/include/asm/dma.h:9:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writeb(value, PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
>> mm/page_owner.c:102:3: error: field designator 'using_shared_flags' does not refer to any field in type 'struct page_ext_operations'; did you mean 'using_shared_ext_flags'?
.using_shared_flags = true,
^~~~~~~~~~~~~~~~~~
using_shared_ext_flags
include/linux/page_ext.h:15:7: note: 'using_shared_ext_flags' declared here
bool using_shared_ext_flags;
^
6 warnings and 1 error generated.
vim +102 mm/page_owner.c
97
98 struct page_ext_operations page_owner_ops = {
99 .size = sizeof(struct page_owner),
100 .need = need_page_owner,
101 .init = init_page_owner,
> 102 .using_shared_flags = true,
103 };
104
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h index 22be4582faae..29909e135052 100644 --- a/include/linux/page_ext.h +++ b/include/linux/page_ext.h @@ -12,10 +12,14 @@ struct page_ext_operations { size_t size; bool (*need)(void); void (*init)(void); + bool using_shared_ext_flags; }; #ifdef CONFIG_PAGE_EXTENSION +/* + * The page_ext_flags users must set using_shared_ext_flags to true. + */ enum page_ext_flags { PAGE_EXT_OWNER, PAGE_EXT_OWNER_ALLOCATED, @@ -31,6 +35,9 @@ enum page_ext_flags { * page_ext helps us add more information about the page. * All page_ext are allocated at boot or memory hotplug event, * then the page_ext for pfn always exists. + * Note: that if none of the users of page_ext is setting + * using_shared_ext_flags to true, the field cannot be used, + * as it will be overlapped with another data. */ struct page_ext { unsigned long flags; diff --git a/mm/page_ext.c b/mm/page_ext.c index 4ee522fd381c..7443a797b96b 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -71,6 +71,7 @@ static bool need_page_idle(void) } static struct page_ext_operations page_idle_ops __initdata = { .need = need_page_idle, + .using_shared_ext_flags = true, }; #endif @@ -86,7 +87,7 @@ static struct page_ext_operations *page_ext_ops[] __initdata = { #endif }; -unsigned long page_ext_size = sizeof(struct page_ext); +unsigned long page_ext_size; static unsigned long total_usage; static struct page_ext *lookup_page_ext(const struct page *page); @@ -105,6 +106,15 @@ static bool __init invoke_need_callbacks(void) int entries = ARRAY_SIZE(page_ext_ops); bool need = false; + for (i = 0; i < entries; i++) { + if (page_ext_ops[i]->need && page_ext_ops[i]->need()) { + if (page_ext_ops[i]->using_shared_ext_flags) { + page_ext_size = sizeof(struct page_ext); + break; + } + } + } + for (i = 0; i < entries; i++) { if (page_ext_ops[i]->need && page_ext_ops[i]->need()) { page_ext_ops[i]->offset = page_ext_size; diff --git a/mm/page_owner.c b/mm/page_owner.c index 2d27f532df4c..612a988373cc 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -99,6 +99,7 @@ struct page_ext_operations page_owner_ops = { .size = sizeof(struct page_owner), .need = need_page_owner, .init = init_page_owner, + .using_shared_flags = true, }; static inline struct page_owner *get_page_owner(struct page_ext *page_ext) diff --git a/mm/page_table_check.c b/mm/page_table_check.c index 93e633c1d587..74cfe89d5f53 100644 --- a/mm/page_table_check.c +++ b/mm/page_table_check.c @@ -45,6 +45,7 @@ struct page_ext_operations page_table_check_ops = { .size = sizeof(struct page_table_check), .need = need_page_table_check, .init = init_page_table_check, + .using_shared_ext_flags = false, }; static struct page_table_check *get_page_table_check(struct page_ext *page_ext)
There is 8 byte page_ext->flags field allocated per page whenever CONFIG_PAGE_EXTENSION is enabled. However, not every user of page_ext uses flags. Therefore, check whether flags is needed at least by one user and if so allocate space for it. For example when page_table_check is enabled, on a machine with 128G of memory before the fix: [ 2.244288] allocated 536870912 bytes of page_ext after the fix: [ 2.160154] allocated 268435456 bytes of page_ext Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> --- include/linux/page_ext.h | 7 +++++++ mm/page_ext.c | 12 +++++++++++- mm/page_owner.c | 1 + mm/page_table_check.c | 1 + 4 files changed, 20 insertions(+), 1 deletion(-)