[linux-rt-devel:linux-5.14.y-rt-rebase 184/245] mm/vmalloc.c:1887:2: warning: Value stored to 'cpu' is never read [clang-analyzer-deadcode.DeadStores]

From: kernel test robot
Date: Mon Aug 16 2021 - 19:49:07 EST

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tree: https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-5.14.y-rt-rebase
head: 0eead4e5a60cb716ec911a552787a69332cf6943
commit: 9584df5e521f3b4e0a2063d7878762f7aa54fca5 [184/245] mm/vmalloc: Another preempt disable region which sucks
config: riscv-randconfig-c006-20210816 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 44d0a99a12ec7ead4d2f5ef649ba05b40f6d463d)
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 riscv cross compiling tool for clang build
# apt-get install binutils-riscv64-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/commit/?id=9584df5e521f3b4e0a2063d7878762f7aa54fca5
git remote add linux-rt-devel https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
git fetch --no-tags linux-rt-devel linux-5.14.y-rt-rebase
git checkout 9584df5e521f3b4e0a2063d7878762f7aa54fca5
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=riscv clang-analyzer

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

clang-analyzer warnings: (new ones prefixed by >>)
^~~~~
include/asm-generic/bitops/fls.h:17:6: note: Assuming 'x' is not equal to 0, which participates in a condition later
if (!x)
^~
include/asm-generic/bitops/fls.h:17:2: note: Taking false branch
if (!x)
^
include/asm-generic/bitops/fls.h:19:6: note: Assuming the condition is false
if (!(x & 0xffff0000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:19:2: note: Taking false branch
if (!(x & 0xffff0000u)) {
^
include/asm-generic/bitops/fls.h:23:6: note: Assuming the condition is false
if (!(x & 0xff000000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:23:2: note: Taking false branch
if (!(x & 0xff000000u)) {
^
include/asm-generic/bitops/fls.h:27:6: note: Assuming the condition is false
if (!(x & 0xf0000000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:27:2: note: Taking false branch
if (!(x & 0xf0000000u)) {
^
include/asm-generic/bitops/fls.h:31:6: note: Assuming the condition is false
if (!(x & 0xc0000000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:31:2: note: Taking false branch
if (!(x & 0xc0000000u)) {
^
include/asm-generic/bitops/fls.h:35:6: note: Assuming the condition is false
if (!(x & 0x80000000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:35:2: note: Taking false branch
if (!(x & 0x80000000u)) {
^
include/asm-generic/bitops/fls.h:39:2: note: Returning the value 32 (loaded from 'r')
return r;
^~~~~~~~
include/linux/bitops.h:188:10: note: Returning from 'fls'
return fls(l);
^~~~~~
include/linux/bitops.h:188:3: note: Returning the value 32
return fls(l);
^~~~~~~~~~~~~
include/linux/log2.h:57:16: note: Returning from 'fls_long'
return 1UL << fls_long(n - 1);
^~~~~~~~~~~~~~~
include/linux/log2.h:57:13: note: The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'unsigned long'
return 1UL << fls_long(n - 1);
^ ~~~~~~~~~~~~~~~
Suppressed 14 warnings (14 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
8 warnings generated.
Suppressed 8 warnings (8 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
8 warnings generated.
Suppressed 8 warnings (8 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
9 warnings generated.
Suppressed 9 warnings (9 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
17 warnings generated.
mm/vmalloc.c:285:2: warning: Value stored to 'start' is never read [clang-analyzer-deadcode.DeadStores]
start = addr;
^ ~~~~
mm/vmalloc.c:285:2: note: Value stored to 'start' is never read
start = addr;
^ ~~~~
mm/vmalloc.c:568:18: warning: Value stored to 'nr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
unsigned int i, nr = (end - addr) >> PAGE_SHIFT;
^~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/vmalloc.c:568:18: note: Value stored to 'nr' during its initialization is never read
unsigned int i, nr = (end - addr) >> PAGE_SHIFT;
^~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
>> mm/vmalloc.c:1887:2: warning: Value stored to 'cpu' is never read [clang-analyzer-deadcode.DeadStores]
cpu = get_cpu_light();
^
mm/vmalloc.c:1887:2: note: Value stored to 'cpu' is never read
mm/vmalloc.c:1972:2: warning: Value stored to 'cpu' is never read [clang-analyzer-deadcode.DeadStores]
cpu = get_cpu_light();
^
mm/vmalloc.c:1972:2: note: Value stored to 'cpu' is never read
mm/vmalloc.c:1978:23: warning: The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'unsigned long' [clang-analyzer-core.UndefinedBinaryOperatorResult]
if (vb->free < (1UL << order)) {
^ ~~~~~
mm/vmalloc.c:1959:2: note: Assuming the condition is true
BUG_ON(offset_in_page(size));
^
include/asm-generic/bug.h:65:36: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:78:40: note: expanded from macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^~~~
mm/vmalloc.c:1959:2: note: Taking false branch
BUG_ON(offset_in_page(size));
^
include/asm-generic/bug.h:65:32: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^
mm/vmalloc.c:1959:2: note: Loop condition is false. Exiting loop
BUG_ON(offset_in_page(size));
^
include/asm-generic/bug.h:65:27: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^
mm/vmalloc.c:1960:9: note: Assuming the condition is false
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
^
include/asm-generic/bug.h:65:45: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
~~~~~~~~~^~~~~~~~~~
include/linux/compiler.h:78:42: note: expanded from macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
mm/vmalloc.c:1960:2: note: Taking false branch
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
^
include/asm-generic/bug.h:65:32: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^
mm/vmalloc.c:1960:2: note: Loop condition is false. Exiting loop
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
^
include/asm-generic/bug.h:65:27: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^
mm/vmalloc.c:1961:14: note: Assuming 'size' is not equal to 0
if (WARN_ON(size == 0)) {
^
include/asm-generic/bug.h:121:25: note: expanded from macro 'WARN_ON'
int __ret_warn_on = !!(condition); \
^~~~~~~~~
mm/vmalloc.c:1961:6: note: Taking false branch
if (WARN_ON(size == 0)) {
^
include/asm-generic/bug.h:122:2: note: expanded from macro 'WARN_ON'
if (unlikely(__ret_warn_on)) \
^
mm/vmalloc.c:1961:2: note: Taking false branch
if (WARN_ON(size == 0)) {
^
mm/vmalloc.c:1969:10: note: Calling 'get_order'
order = get_order(size);
^~~~~~~~~~~~~~~
include/asm-generic/getorder.h:31:2: note: Taking false branch
if (__builtin_constant_p(size)) {
^
include/asm-generic/getorder.h:44:9: note: Calling 'fls'
return fls(size);
^~~~~~~~~
include/asm-generic/bitops/fls.h:15:2: note: 'r' initialized to 32
int r = 32;
^~~~~
include/asm-generic/bitops/fls.h:17:6: note: Assuming 'x' is not equal to 0, which participates in a condition later
if (!x)
^~
include/asm-generic/bitops/fls.h:17:2: note: Taking false branch
if (!x)
^
include/asm-generic/bitops/fls.h:19:6: note: Assuming the condition is false
if (!(x & 0xffff0000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:19:2: note: Taking false branch
if (!(x & 0xffff0000u)) {
^
include/asm-generic/bitops/fls.h:23:6: note: Assuming the condition is false
if (!(x & 0xff000000u)) {
^~~~~~~~~~~~~~~~~~
include/asm-generic/bitops/fls.h:23:2: note: Taking false branch
if (!(x & 0xff000000u)) {
^
include/asm-generic/bitops/fls.h:27:6: note: Assuming the condition is false
if (!(x & 0xf0000000u)) {
^~~~~~~~~~~~~~~~~~

vim +/cpu +1887 mm/vmalloc.c

1835
1836 /**
1837 * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
1838 * block. Of course pages number can't exceed VMAP_BBMAP_BITS
1839 * @order: how many 2^order pages should be occupied in newly allocated block
1840 * @gfp_mask: flags for the page level allocator
1841 *
1842 * Return: virtual address in a newly allocated block or ERR_PTR(-errno)
1843 */
1844 static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
1845 {
1846 struct vmap_block_queue *vbq;
1847 struct vmap_block *vb;
1848 struct vmap_area *va;
1849 unsigned long vb_idx;
1850 int node, err, cpu;
1851 void *vaddr;
1852
1853 node = numa_node_id();
1854
1855 vb = kmalloc_node(sizeof(struct vmap_block),
1856 gfp_mask & GFP_RECLAIM_MASK, node);
1857 if (unlikely(!vb))
1858 return ERR_PTR(-ENOMEM);
1859
1860 va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
1861 VMALLOC_START, VMALLOC_END,
1862 node, gfp_mask);
1863 if (IS_ERR(va)) {
1864 kfree(vb);
1865 return ERR_CAST(va);
1866 }
1867
1868 vaddr = vmap_block_vaddr(va->va_start, 0);
1869 spin_lock_init(&vb->lock);
1870 vb->va = va;
1871 /* At least something should be left free */
1872 BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
1873 vb->free = VMAP_BBMAP_BITS - (1UL << order);
1874 vb->dirty = 0;
1875 vb->dirty_min = VMAP_BBMAP_BITS;
1876 vb->dirty_max = 0;
1877 INIT_LIST_HEAD(&vb->free_list);
1878
1879 vb_idx = addr_to_vb_idx(va->va_start);
1880 err = xa_insert(&vmap_blocks, vb_idx, vb, gfp_mask);
1881 if (err) {
1882 kfree(vb);
1883 free_vmap_area(va);
1884 return ERR_PTR(err);
1885 }
1886
> 1887 cpu = get_cpu_light();
1888 vbq = this_cpu_ptr(&vmap_block_queue);
1889 spin_lock(&vbq->lock);
1890 list_add_tail_rcu(&vb->free_list, &vbq->free);
1891 spin_unlock(&vbq->lock);
1892 put_cpu_light();
1893
1894 return vaddr;
1895 }
1896

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
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