On 19 Jul 2017, at 16:59, Andrew Morton wrote:
On Wed, 19 Jul 2017 14:39:43 -0400 "Zi Yan" <zi.yan@xxxxxxxxxxxxxx>
wrote:
On 19 Jul 2017, at 4:04, kbuild test robot wrote:
Hi Zi,
[auto build test WARNING on mmotm/master]
[also build test WARNING on v4.13-rc1 next-20170718]
[if your patch is applied to the wrong git tree, please drop us a
note to help improve the system]
url:
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2F0day-ci%2Flinux%2Fcommits%2FZi-Yan%2Fmm-page-migration-enhancement-for-thp%2F20170718-095519&data=02%7C01%7Czi.yan%40cs.rutgers.edu%7Ca711ac47d4c0436ef66f08d4ce7cf30c%7Cb92d2b234d35447093ff69aca6632ffe%7C1%7C0%7C636360483431631457&sdata=NpxRpWbxe6o56xDJYpw1K6wgQo11IPCAbG2tE8l%2BU6E%3D&reserved=0
base: git://git.cmpxchg.org/linux-mmotm.git master
config: xtensa-common_defconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 4.9.0
reproduce:
wget
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fraw.githubusercontent.com%2F01org%2Flkp-tests%2Fmaster%2Fsbin%2Fmake.cross&data=02%7C01%7Czi.yan%40cs.rutgers.edu%7Ca711ac47d4c0436ef66f08d4ce7cf30c%7Cb92d2b234d35447093ff69aca6632ffe%7C1%7C0%7C636360483431631457&sdata=rBCfu0xUg3v%2B8r%2Be2tsiqRcqw%2FEZSTa4OtF0hU%2FqMbc%3D&reserved=0
-O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=xtensa
All warnings (new ones prefixed by >>):
In file included from mm/vmscan.c:55:0:
include/linux/swapops.h: In function 'swp_entry_to_pmd':
include/linux/swapops.h:220:2: warning: missing braces around
initializer [-Wmissing-braces]
return (pmd_t){ 0 };
^
include/linux/swapops.h:220:2: warning: (near initialization for
'(anonymous).pud') [-Wmissing-braces]
vim +220 include/linux/swapops.h
217
218 static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
219 {
220 return (pmd_t){ 0 };
221 }
222
It is a GCC 4.9.0 bug:
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fbugzilla%2Fshow_bug.cgi%3Fid%3D53119&data=02%7C01%7Czi.yan%40cs.rutgers.edu%7C07c903c4f1444958942508d4cee90ca7%7Cb92d2b234d35447093ff69aca6632ffe%7C1%7C0%7C636360947714283172&sdata=84%2BXG7hglTCsTjGA8G3jyL7%2BFupkQaMkjAwzofffA5A%3D&reserved=0
Upgrading GCC can get rid of this warning.
I think there was a workaround for this, but I don't recall what it
was.
This suppressed the warning:
--- a/include/linux/swapops.h~a
+++ a/include/linux/swapops.h
@@ -217,7 +217,7 @@ static inline swp_entry_t pmd_to_swp_ent
static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
{
- return (pmd_t){ 0 };
+ return (pmd_t){};
}
static inline int is_pmd_migration_entry(pmd_t pmd)
But I don't know if this is the approved workaround and I don't know
what it will do at runtime!
But we should fix this. Expecting zillions of people to update their
compiler version isn't nice.
How about this one?
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -219,7 +219,7 @@ static inline swp_entry_t pmd_to_swp_entry(pmd_t
pmd)
static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
{
- return (pmd_t){ 0 };
+ return __pmd(0);
}
static inline int is_pmd_migration_entry(pmd_t pmd)
No warning or error was present during i386 kernel compilations
with gcc-4.9.3 or gcc-6.4.0. i386 gcc should share the same front-end
as xtensa-linux-gcc.
__pmd() should be the standard way of making pmd entries, right?
--
Best Regards
Yan Zi
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