tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git urezki-pcount.2020.09.26a head: e9bed2a1239b017d78cec5de66adce0560f6d077 commit: 2fa3b3dd18ef5ef28a9dd40f6711211c62ac929b [5/17] mm/pagemap: Cleanup PREEMPT_COUNT leftovers config: x86_64-randconfig-a002-20200927 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project a83eb048cb9a75da7a07a9d5318bbdbf54885c87) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=2fa3b3dd18ef5ef28a9dd40f6711211c62ac929b git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git git fetch --no-tags rcu urezki-pcount.2020.09.26a git checkout 2fa3b3dd18ef5ef28a9dd40f6711211c62ac929b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>
All errors (new ones prefixed by >>):
In file included from arch/x86/kernel/asm-offsets.c:13:
In file included from include/linux/suspend.h:5:
In file included from include/linux/swap.h:9:
In file included from include/linux/memcontrol.h:22:
In file included from include/linux/writeback.h:14:
In file included from include/linux/blk-cgroup.h:23:
In file included from include/linux/blkdev.h:13:
>> include/linux/pagemap.h:181:2: error: called object type 'void' is not a
>> function or function pointer
VM_BUG_ON_PAGE(page_count(page) == 0, page);
^
include/linux/mmdebug.h:46:36: note: expanded from macro 'VM_BUG_ON_PAGE'
#define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)
^
include/linux/mmdebug.h:45:25: note: expanded from macro 'VM_BUG_ON'
#define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)
^
include/linux/build_bug.h:30:33: note: expanded from macro
'BUILD_BUG_ON_INVALID'
#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
^
1 error generated.
make[2]: *** [scripts/Makefile.build:117: arch/x86/kernel/asm-offsets.s]
Error 1
make[2]: Target '__build' not remade because of errors.
make[1]: *** [Makefile:1198: prepare0] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:185: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
vim +/void +181 include/linux/pagemap.h
^1da177e4c3f41 Linus Torvalds 2005-04-16 123
e286781d5f2e9c Nick Piggin 2008-07-25 124 /*
e286781d5f2e9c Nick Piggin 2008-07-25 125 * speculatively take a
reference to a page.
0139aa7b7fa12c Joonsoo Kim 2016-05-19 126 * If the page is free
(_refcount == 0), then _refcount is untouched, and 0
0139aa7b7fa12c Joonsoo Kim 2016-05-19 127 * is returned.
Otherwise, _refcount is incremented by 1 and 1 is returned.
e286781d5f2e9c Nick Piggin 2008-07-25 128 *
e286781d5f2e9c Nick Piggin 2008-07-25 129 * This function must be
called inside the same rcu_read_lock() section as has
e286781d5f2e9c Nick Piggin 2008-07-25 130 * been used to lookup
the page in the pagecache radix-tree (or page table):
0139aa7b7fa12c Joonsoo Kim 2016-05-19 131 * this allows
allocators to use a synchronize_rcu() to stabilize _refcount.
e286781d5f2e9c Nick Piggin 2008-07-25 132 *
e286781d5f2e9c Nick Piggin 2008-07-25 133 * Unless an RCU grace
period has passed, the count of all pages coming out
e286781d5f2e9c Nick Piggin 2008-07-25 134 * of the allocator must
be considered unstable. page_count may return higher
e286781d5f2e9c Nick Piggin 2008-07-25 135 * than expected, and
put_page must be able to do the right thing when the
e286781d5f2e9c Nick Piggin 2008-07-25 136 * page has been
finished with, no matter what it is subsequently allocated
e286781d5f2e9c Nick Piggin 2008-07-25 137 * for (because put_page
is what is used here to drop an invalid speculative
e286781d5f2e9c Nick Piggin 2008-07-25 138 * reference).
e286781d5f2e9c Nick Piggin 2008-07-25 139 *
e286781d5f2e9c Nick Piggin 2008-07-25 140 * This is the
interesting part of the lockless pagecache (and lockless
e286781d5f2e9c Nick Piggin 2008-07-25 141 * get_user_pages)
locking protocol, where the lookup-side (eg. find_get_page)
e286781d5f2e9c Nick Piggin 2008-07-25 142 * has the following
pattern:
e286781d5f2e9c Nick Piggin 2008-07-25 143 * 1. find page in radix
tree
e286781d5f2e9c Nick Piggin 2008-07-25 144 * 2. conditionally
increment refcount
e286781d5f2e9c Nick Piggin 2008-07-25 145 * 3. check the page is
still in pagecache (if no, goto 1)
e286781d5f2e9c Nick Piggin 2008-07-25 146 *
0139aa7b7fa12c Joonsoo Kim 2016-05-19 147 * Remove-side that
cares about stability of _refcount (eg. reclaim) has the
b93b016313b3ba Matthew Wilcox 2018-04-10 148 * following (with the
i_pages lock held):
e286781d5f2e9c Nick Piggin 2008-07-25 149 * A. atomically check
refcount is correct and set it to 0 (atomic_cmpxchg)
e286781d5f2e9c Nick Piggin 2008-07-25 150 * B. remove page from
pagecache
e286781d5f2e9c Nick Piggin 2008-07-25 151 * C. free the page
e286781d5f2e9c Nick Piggin 2008-07-25 152 *
e286781d5f2e9c Nick Piggin 2008-07-25 153 * There are 2 critical
interleavings that matter:
e286781d5f2e9c Nick Piggin 2008-07-25 154 * - 2 runs before A: in
this case, A sees elevated refcount and bails out
e286781d5f2e9c Nick Piggin 2008-07-25 155 * - A runs before 2: in
this case, 2 sees zero refcount and retries;
e286781d5f2e9c Nick Piggin 2008-07-25 156 * subsequently, B
will complete and 1 will find no page, causing the
e286781d5f2e9c Nick Piggin 2008-07-25 157 * lookup to return
NULL.
e286781d5f2e9c Nick Piggin 2008-07-25 158 *
e286781d5f2e9c Nick Piggin 2008-07-25 159 * It is possible that
between 1 and 2, the page is removed then the exact same
e286781d5f2e9c Nick Piggin 2008-07-25 160 * page is inserted into
the same position in pagecache. That's OK: the
b93b016313b3ba Matthew Wilcox 2018-04-10 161 * old find_get_page
using a lock could equally have run before or after
e286781d5f2e9c Nick Piggin 2008-07-25 162 * such a re-insertion,
depending on order that locks are granted.
e286781d5f2e9c Nick Piggin 2008-07-25 163 *
e286781d5f2e9c Nick Piggin 2008-07-25 164 * Lookups racing
against pagecache insertion isn't a big problem: either 1
e286781d5f2e9c Nick Piggin 2008-07-25 165 * will find the page or
it will not. Likewise, the old find_get_page could run
e286781d5f2e9c Nick Piggin 2008-07-25 166 * either before the
insertion or afterwards, depending on timing.
e286781d5f2e9c Nick Piggin 2008-07-25 167 */
494eec70f05496 john.hubb...@gmail.com 2019-03-05 168 static inline int
__page_cache_add_speculative(struct page *page, int count)
e286781d5f2e9c Nick Piggin 2008-07-25 169 {
8375ad98cc1def Paul E. McKenney 2013-04-29 170 #ifdef CONFIG_TINY_RCU
2fa3b3dd18ef5e Thomas Gleixner 2020-09-14 171 VM_BUG_ON(preemptible())
e286781d5f2e9c Nick Piggin 2008-07-25 172 /*
e286781d5f2e9c Nick Piggin 2008-07-25 173 * Preempt must be
disabled here - we rely on rcu_read_lock doing
e286781d5f2e9c Nick Piggin 2008-07-25 174 * this for us.
e286781d5f2e9c Nick Piggin 2008-07-25 175 *
e286781d5f2e9c Nick Piggin 2008-07-25 176 * Pagecache won't be
truncated from interrupt context, so if we have
e286781d5f2e9c Nick Piggin 2008-07-25 177 * found a page in the
radix tree here, we have pinned its refcount by
e286781d5f2e9c Nick Piggin 2008-07-25 178 * disabling preempt,
and hence no need for the "speculative get" that
e286781d5f2e9c Nick Piggin 2008-07-25 179 * SMP requires.
e286781d5f2e9c Nick Piggin 2008-07-25 180 */
309381feaee564 Sasha Levin 2014-01-23 @181
VM_BUG_ON_PAGE(page_count(page) == 0, page);
494eec70f05496 john.hubb...@gmail.com 2019-03-05 182 page_ref_add(page,
count);
e286781d5f2e9c Nick Piggin 2008-07-25 183
:::::: The code at line 181 was first introduced by commit
:::::: 309381feaee564281c3d9e90fbca8963bb7428ad mm: dump page when hitting a
VM_BUG_ON using VM_BUG_ON_PAGE
:::::: TO: Sasha Levin <sasha.le...@oracle.com>
:::::: CC: Linus Torvalds <torva...@linux-foundation.org>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org
.config.gz
Description: application/gzip
