From: Christian Brauner <brauner@kernel.org>
To: Baokun Li <libaokun1@huawei.com>
Cc: kernel test robot <lkp@intel.com>,
sfr@canb.auug.org.au, llvm@lists.linux.dev,
oe-kbuild-all@lists.linux.dev,
Christian Brauner <christianvanbrauner@gmail.com>,
yangerkun <yangerkun@huawei.com>,
"zhangyi (F)" <yi.zhang@huawei.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-next@vger.kernel.org
Subject: Re: [brauner-vfs:vfs.misc 12/13] include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
Date: Tue, 23 Jan 2024 17:24:03 +0100 [thread overview]
Message-ID: <20240123-glatt-langgehegter-a239e588ae2c@brauner> (raw)
In-Reply-To: <59fae3eb-a125-cd5f-224e-b89d122ecb46@huawei.com>
On Tue, Jan 23, 2024 at 03:07:50PM +0800, Baokun Li wrote:
> On 2024/1/23 8:12, kernel test robot wrote:
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.misc
> > head: 297983dc9011461cba6278bfe03f4305c4a2caa0
> > commit: 4bbd51d0f0ad709c0f02c100439d6c9ba6811d4b [12/13] fs: make the i_size_read/write helpers be smp_load_acquire/store_release()
> > config: i386-randconfig-015-20240123 (https://download.01.org/0day-ci/archive/20240123/202401230837.TXro0PHi-lkp@intel.com/config)
> > compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240123/202401230837.TXro0PHi-lkp@intel.com/reproduce)
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202401230837.TXro0PHi-lkp@intel.com/
> >
> > All errors (new ones prefixed by >>):
> >
> > In file included from fs/netfs/buffered_read.c:10:
> > In file included from fs/netfs/internal.h:9:
> > In file included from include/linux/seq_file.h:12:
> > > > include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
> > 911 | return smp_load_acquire(&inode->i_size);
> > | ^
> > include/asm-generic/barrier.h:206:2: note: expanded from macro 'smp_load_acquire'
> > 206 | compiletime_assert_atomic_type(*p); \
> > | ^
> > include/linux/compiler_types.h:438:2: note: expanded from macro 'compiletime_assert_atomic_type'
> > 438 | compiletime_assert(__native_word(t), \
> > | ^
> > include/linux/compiler_types.h:435:2: note: expanded from macro 'compiletime_assert'
> > 435 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> > | ^
> > include/linux/compiler_types.h:423:2: note: expanded from macro '_compiletime_assert'
> > 423 | __compiletime_assert(condition, msg, prefix, suffix)
> > | ^
> > include/linux/compiler_types.h:416:4: note: expanded from macro '__compiletime_assert'
> > 416 | prefix ## suffix(); \
> > | ^
> > <scratch space>:38:1: note: expanded from here
> > 38 | __compiletime_assert_207
> > | ^
> > 1 error generated.
> > --
> > In file included from fs/netfs/buffered_write.c:9:
> > > > include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
> > 911 | return smp_load_acquire(&inode->i_size);
> > | ^
> > include/asm-generic/barrier.h:206:2: note: expanded from macro 'smp_load_acquire'
> > 206 | compiletime_assert_atomic_type(*p); \
> > | ^
> > include/linux/compiler_types.h:438:2: note: expanded from macro 'compiletime_assert_atomic_type'
> > 438 | compiletime_assert(__native_word(t), \
> > | ^
> > include/linux/compiler_types.h:435:2: note: expanded from macro 'compiletime_assert'
> > 435 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> > | ^
> > include/linux/compiler_types.h:423:2: note: expanded from macro '_compiletime_assert'
> > 423 | __compiletime_assert(condition, msg, prefix, suffix)
> > | ^
> > include/linux/compiler_types.h:416:4: note: expanded from macro '__compiletime_assert'
> > 416 | prefix ## suffix(); \
> > | ^
> > <scratch space>:253:1: note: expanded from here
> > 253 | __compiletime_assert_207
> > | ^
> > In file included from fs/netfs/buffered_write.c:9:
> > > > include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
> > include/asm-generic/barrier.h:206:2: note: expanded from macro 'smp_load_acquire'
> > 206 | compiletime_assert_atomic_type(*p); \
> > | ^
> > include/linux/compiler_types.h:438:2: note: expanded from macro 'compiletime_assert_atomic_type'
> > 438 | compiletime_assert(__native_word(t), \
> > | ^
> > include/linux/compiler_types.h:435:2: note: expanded from macro 'compiletime_assert'
> > 435 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> > | ^
> > include/linux/compiler_types.h:423:2: note: expanded from macro '_compiletime_assert'
> > 423 | __compiletime_assert(condition, msg, prefix, suffix)
> > | ^
> > include/linux/compiler_types.h:416:4: note: expanded from macro '__compiletime_assert'
> > 416 | prefix ## suffix(); \
> > | ^
> > <scratch space>:253:1: note: expanded from here
> > 253 | __compiletime_assert_207
> > | ^
> > In file included from fs/netfs/buffered_write.c:9:
> > > > include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
> > include/asm-generic/barrier.h:206:2: note: expanded from macro 'smp_load_acquire'
> > 206 | compiletime_assert_atomic_type(*p); \
> > | ^
> > include/linux/compiler_types.h:438:2: note: expanded from macro 'compiletime_assert_atomic_type'
> > 438 | compiletime_assert(__native_word(t), \
> > | ^
> > include/linux/compiler_types.h:435:2: note: expanded from macro 'compiletime_assert'
> > 435 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> > | ^
> > include/linux/compiler_types.h:423:2: note: expanded from macro '_compiletime_assert'
> > 423 | __compiletime_assert(condition, msg, prefix, suffix)
> > | ^
> > include/linux/compiler_types.h:416:4: note: expanded from macro '__compiletime_assert'
> > 416 | prefix ## suffix(); \
> > | ^
> > <scratch space>:253:1: note: expanded from here
> > 253 | __compiletime_assert_207
> > | ^
> > In file included from fs/netfs/buffered_write.c:9:
> > > > include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
> > include/asm-generic/barrier.h:206:2: note: expanded from macro 'smp_load_acquire'
> > 206 | compiletime_assert_atomic_type(*p); \
> > | ^
> > include/linux/compiler_types.h:438:2: note: expanded from macro 'compiletime_assert_atomic_type'
> > 438 | compiletime_assert(__native_word(t), \
> > | ^
> > include/linux/compiler_types.h:435:2: note: expanded from macro 'compiletime_assert'
> > 435 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> > | ^
> > include/linux/compiler_types.h:423:2: note: expanded from macro '_compiletime_assert'
> > 423 | __compiletime_assert(condition, msg, prefix, suffix)
> > | ^
> > include/linux/compiler_types.h:416:4: note: expanded from macro '__compiletime_assert'
> > 416 | prefix ## suffix(); \
> > | ^
> > <scratch space>:253:1: note: expanded from here
> > 253 | __compiletime_assert_207
> > | ^
> > 4 errors generated.
> > --
> > In file included from fs/netfs/misc.c:8:
> > In file included from include/linux/swap.h:9:
> > In file included from include/linux/memcontrol.h:13:
> > In file included from include/linux/cgroup.h:17:
> > > > include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity.
> > 911 | return smp_load_acquire(&inode->i_size);
> > | ^
> > include/asm-generic/barrier.h:206:2: note: expanded from macro 'smp_load_acquire'
> > 206 | compiletime_assert_atomic_type(*p); \
> > | ^
> > include/linux/compiler_types.h:438:2: note: expanded from macro 'compiletime_assert_atomic_type'
> > 438 | compiletime_assert(__native_word(t), \
> > | ^
> > include/linux/compiler_types.h:435:2: note: expanded from macro 'compiletime_assert'
> > 435 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> > | ^
> > include/linux/compiler_types.h:423:2: note: expanded from macro '_compiletime_assert'
> > 423 | __compiletime_assert(condition, msg, prefix, suffix)
> > | ^
> > include/linux/compiler_types.h:416:4: note: expanded from macro '__compiletime_assert'
> > 416 | prefix ## suffix(); \
> > | ^
> > <scratch space>:251:1: note: expanded from here
> > 251 | __compiletime_assert_207
> > | ^
> > 1 error generated.
> >
> > Kconfig warnings: (for reference only)
> > WARNING: unmet direct dependencies detected for DRM_I915_DEBUG_GEM
> > Depends on [n]: HAS_IOMEM [=y] && DRM_I915 [=y] && EXPERT [=y] && DRM_I915_WERROR [=n]
> > Selected by [y]:
> > - DRM_I915_DEBUG [=y] && HAS_IOMEM [=y] && DRM_I915 [=y] && EXPERT [=y] && !COMPILE_TEST [=n]
> >
> >
> > vim +911 include/linux/fs.h
> >
> > 874
> > 875 void filemap_invalidate_lock_two(struct address_space *mapping1,
> > 876 struct address_space *mapping2);
> > 877 void filemap_invalidate_unlock_two(struct address_space *mapping1,
> > 878 struct address_space *mapping2);
> > 879
> > 880
> > 881 /*
> > 882 * NOTE: in a 32bit arch with a preemptable kernel and
> > 883 * an UP compile the i_size_read/write must be atomic
> > 884 * with respect to the local cpu (unlike with preempt disabled),
> > 885 * but they don't need to be atomic with respect to other cpus like in
> > 886 * true SMP (so they need either to either locally disable irq around
> > 887 * the read or for example on x86 they can be still implemented as a
> > 888 * cmpxchg8b without the need of the lock prefix). For SMP compiles
> > 889 * and 64bit archs it makes no difference if preempt is enabled or not.
> > 890 */
> > 891 static inline loff_t i_size_read(const struct inode *inode)
> > 892 {
> > 893 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
> > 894 loff_t i_size;
> > 895 unsigned int seq;
> > 896
> > 897 do {
> > 898 seq = read_seqcount_begin(&inode->i_size_seqcount);
> > 899 i_size = inode->i_size;
> > 900 } while (read_seqcount_retry(&inode->i_size_seqcount, seq));
> > 901 return i_size;
> > 902 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)
> > 903 loff_t i_size;
> > 904
> > 905 preempt_disable();
> > 906 i_size = inode->i_size;
> > 907 preempt_enable();
> > 908 return i_size;
> > 909 #else
> > 910 /* Pairs with smp_store_release() in i_size_write() */
> > > 911 return smp_load_acquire(&inode->i_size);
> > 912 #endif
> > 913 }
> > 914
> Sorry to cause this compilation error, I have not encountered this
> before when testing compilation with gcc on x86 and arm64.
> Is there a special config required for this, or is it just clang that
> triggers this compile error?
>
> The compile error seems to be that some architectural implementations
> of smp_load_acquire() do not support pointers to long long data
> types. Can't think of a good way to avoid this problem, any ideas
> from linus and christian?
That code in i_size_{read,write}() is terrible to look at.
Pragmatically, we can probably just do READ_ONCE() + smp_rmb() and
smp_wmb() + WRITE_ONCE(). This guarantees the ordering and it works
(compiles) on 32bit as well. I think it's still possible that on 32bit
the READ_ONCE()/WRITE_ONCE() are compiled as two accesses. But I'm not
sure that this matters because iiuc that problem would've already been
there with the barrier in mm/filemap.c instead of here.
next prev parent reply other threads:[~2024-01-23 16:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <202401230837.TXro0PHi-lkp@intel.com>
2024-01-23 7:07 ` [brauner-vfs:vfs.misc 12/13] include/linux/fs.h:911:9: error: call to '__compiletime_assert_207' declared with 'error' attribute: Need native word sized stores/loads for atomicity Baokun Li
2024-01-23 16:24 ` Christian Brauner [this message]
2024-01-24 7:52 ` Baokun Li
2024-01-24 10:30 ` Christian Brauner
2024-01-24 11:53 ` Baokun Li
2024-01-24 13:27 ` Christian Brauner
2024-01-24 13:38 ` Baokun Li
2024-01-23 17:46 ` Linus Torvalds
2024-01-24 7:31 ` Baokun Li
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