From: kernel test robot <lkp@intel.com>
To: kbuild@lists.01.org
Subject: [rppt:gfp-unmapped/v0 1/3] mm/page_alloc.c:2656:16: warning: Value stored to 'start_addr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
Date: Sat, 22 Jan 2022 06:47:39 +0800 [thread overview]
Message-ID: <202201220612.bMAwh2Bt-lkp@intel.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 16936 bytes --]
CC: llvm(a)lists.linux.dev
CC: kbuild-all(a)lists.01.org
CC: Mike Rapoport <rppt@kernel.org>
CC: linux-kernel(a)vger.kernel.org
TO: Mike Rapoport <rppt@linux.ibm.com>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git gfp-unmapped/v0
head: 53acd000a0eef1457aaa4930c0d2003d7785f799
commit: 253f456a5cb652a16a59cc4ac2e18669997d79cd [1/3] mm/page_alloc: introduce __GFP_UNMAPPED and MIGRETE_UNMAPPED
:::::: branch date: 34 hours ago
:::::: commit date: 35 hours ago
config: x86_64-randconfig-c007 (https://download.01.org/0day-ci/archive/20220122/202201220612.bMAwh2Bt-lkp(a)intel.com/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project d4baf3b1322b84816aa623d8e8cb45a49cb68b84)
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://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/commit/?id=253f456a5cb652a16a59cc4ac2e18669997d79cd
git remote add rppt https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git
git fetch --no-tags rppt gfp-unmapped/v0
git checkout 253f456a5cb652a16a59cc4ac2e18669997d79cd
# save the config file to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 clang-analyzer
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
clang-analyzer warnings: (new ones prefixed by >>)
^
mm/page_alloc.c:1512:20: note: Left side of '||' is true
int prefetch_nr = READ_ONCE(pcp->batch);
^
include/asm-generic/rwonce.h:49:2: note: expanded from macro 'READ_ONCE'
compiletime_assert_rwonce_type(x); \
^
include/asm-generic/rwonce.h:36:21: note: expanded from macro 'compiletime_assert_rwonce_type'
compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
^
include/linux/compiler_types.h:314:28: note: expanded from macro '__native_word'
sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
^
mm/page_alloc.c:1512:20: note: Taking false branch
int prefetch_nr = READ_ONCE(pcp->batch);
^
include/asm-generic/rwonce.h:49:2: note: expanded from macro 'READ_ONCE'
compiletime_assert_rwonce_type(x); \
^
include/asm-generic/rwonce.h:36:2: note: expanded from macro 'compiletime_assert_rwonce_type'
compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
^
include/linux/compiler_types.h:346:2: note: expanded from macro 'compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^
include/linux/compiler_types.h:334:2: note: expanded from macro '_compiletime_assert'
__compiletime_assert(condition, msg, prefix, suffix)
^
include/linux/compiler_types.h:326:3: note: expanded from macro '__compiletime_assert'
if (!(condition)) \
^
mm/page_alloc.c:1512:20: note: Loop condition is false. Exiting loop
int prefetch_nr = READ_ONCE(pcp->batch);
^
include/asm-generic/rwonce.h:49:2: note: expanded from macro 'READ_ONCE'
compiletime_assert_rwonce_type(x); \
^
include/asm-generic/rwonce.h:36:2: note: expanded from macro 'compiletime_assert_rwonce_type'
compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
^
include/linux/compiler_types.h:346:2: note: expanded from macro 'compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^
include/linux/compiler_types.h:334:2: note: expanded from macro '_compiletime_assert'
__compiletime_assert(condition, msg, prefix, suffix)
^
include/linux/compiler_types.h:318:2: note: expanded from macro '__compiletime_assert'
do { \
^
mm/page_alloc.c:1521:10: note: '__UNIQUE_ID___x910' is >= '__UNIQUE_ID___y911'
count = min(pcp->count, count);
^
include/linux/minmax.h:45:19: note: expanded from macro 'min'
#define min(x, y) __careful_cmp(x, y, <)
^~~~~~~~~~~~~~~~~~~~~~
include/linux/minmax.h:38:3: note: expanded from macro '__careful_cmp'
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/minmax.h:33:3: note: expanded from macro '__cmp_once'
__cmp(unique_x, unique_y, op); })
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/minmax.h:28:26: note: expanded from macro '__cmp'
#define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
^~~
mm/page_alloc.c:1521:10: note: '?' condition is false
count = min(pcp->count, count);
^
include/linux/minmax.h:45:19: note: expanded from macro 'min'
#define min(x, y) __careful_cmp(x, y, <)
^
include/linux/minmax.h:38:3: note: expanded from macro '__careful_cmp'
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
^
include/linux/minmax.h:33:3: note: expanded from macro '__cmp_once'
__cmp(unique_x, unique_y, op); })
^
include/linux/minmax.h:28:26: note: expanded from macro '__cmp'
#define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
^
mm/page_alloc.c:1522:9: note: Assuming 'count' is <= 0
while (count > 0) {
^~~~~~~~~
mm/page_alloc.c:1522:2: note: Loop condition is false. Execution continues on line 1576
while (count > 0) {
^
mm/page_alloc.c:1589:2: note: Assigned value is garbage or undefined
list_for_each_entry_safe(page, tmp, &head, lru) {
^
include/linux/list.h:726:7: note: expanded from macro 'list_for_each_entry_safe'
n = list_next_entry(pos, member); \
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/list.h:564:2: note: expanded from macro 'list_next_entry'
list_entry((pos)->member.next, typeof(*(pos)), member)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/list.h:520:2: note: expanded from macro 'list_entry'
container_of(ptr, type, member)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/container_of.h:18:2: note: expanded from macro 'container_of'
void *__mptr = (void *)(ptr); \
^ ~~~~~~~~~~~~~
>> mm/page_alloc.c:2656:16: warning: Value stored to 'start_addr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
unsigned long start_addr = PFN_PHYS(start_pfn);
^~~~~~~~~~
mm/page_alloc.c:2656:16: note: Value stored to 'start_addr' during its initialization is never read
unsigned long start_addr = PFN_PHYS(start_pfn);
^~~~~~~~~~
>> mm/page_alloc.c:2657:16: warning: Value stored to 'end_addr' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
unsigned long end_addr = PFN_PHYS(end_pfn);
^~~~~~~~
mm/page_alloc.c:2657:16: note: Value stored to 'end_addr' during its initialization is never read
unsigned long end_addr = PFN_PHYS(end_pfn);
^~~~~~~~
mm/page_alloc.c:5462:29: warning: Array access (from variable 'page_array') results in a null pointer dereference [clang-analyzer-core.NullDereference]
page_array[nr_populated] = page;
~~~~~~~~~~ ^
mm/page_alloc.c:5364:9: note: Assuming 'page_array' is null
while (page_array && nr_populated < nr_pages && page_array[nr_populated])
^~~~~~~~~~
mm/page_alloc.c:5364:20: note: Left side of '&&' is false
while (page_array && nr_populated < nr_pages && page_array[nr_populated])
^
mm/page_alloc.c:5368:15: note: Assuming 'nr_pages' is > 0
if (unlikely(nr_pages <= 0))
^
include/linux/compiler.h:78:42: note: expanded from macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
mm/page_alloc.c:5368:2: note: Taking false branch
if (unlikely(nr_pages <= 0))
^
mm/page_alloc.c:5372:15: note: 'page_array' is null
if (unlikely(page_array && nr_pages - nr_populated == 0))
^
include/linux/compiler.h:78:42: note: expanded from macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
mm/page_alloc.c:5372:26: note: Left side of '&&' is false
if (unlikely(page_array && nr_pages - nr_populated == 0))
^
mm/page_alloc.c:5372:2: note: Taking false branch
if (unlikely(page_array && nr_pages - nr_populated == 0))
^
mm/page_alloc.c:5376:6: note: Calling 'memcg_kmem_enabled'
if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT))
^~~~~~~~~~~~~~~~~~~~
include/linux/memcontrol.h:1747:2: note: Returning zero, which participates in a condition later
return false;
^~~~~~~~~~~~
mm/page_alloc.c:5376:6: note: Returning from 'memcg_kmem_enabled'
if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT))
^~~~~~~~~~~~~~~~~~~~
mm/page_alloc.c:5376:27: note: Left side of '&&' is false
if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT))
^
mm/page_alloc.c:5380:6: note: Assuming the condition is false
if (nr_pages - nr_populated == 1)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/page_alloc.c:5380:2: note: Taking false branch
if (nr_pages - nr_populated == 1)
^
mm/page_alloc.c:5384:6: note: Assuming the condition is false
if (gfp & __GFP_UNMAPPED)
^~~~~~~~~~~~~~~~~~~~
mm/page_alloc.c:5384:2: note: Taking false branch
if (gfp & __GFP_UNMAPPED)
^
mm/page_alloc.c:5402:7: note: Calling 'prepare_alloc_pages'
if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/page_alloc.c:5288:2: note: Taking false branch
if (cpusets_enabled()) {
^
mm/page_alloc.c:5303:2: note: Taking true branch
might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
^
include/linux/kernel.h:188:35: note: expanded from macro 'might_sleep_if'
#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
^
mm/page_alloc.c:5303:2: note: Loop condition is false. Exiting loop
might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
^
include/linux/kernel.h:188:45: note: expanded from macro 'might_sleep_if'
#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
^
include/linux/kernel.h:138:2: note: expanded from macro 'might_sleep'
do { __might_sleep(__FILE__, __LINE__); might_resched(); } while (0)
^
mm/page_alloc.c:5303:2: note: Loop condition is false. Exiting loop
might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
^
include/linux/kernel.h:188:30: note: expanded from macro 'might_sleep_if'
#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
^
mm/page_alloc.c:5305:2: note: Taking false branch
if (should_fail_alloc_page(gfp_mask, order))
^
mm/page_alloc.c:5321:2: note: Returning the value 1, which participates in a condition later
return true;
^~~~~~~~~~~
mm/page_alloc.c:5402:7: note: Returning from 'prepare_alloc_pages'
if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/page_alloc.c:5402:2: note: Taking false branch
if (!prepare_alloc_pages(gfp, 0, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags))
^
mm/page_alloc.c:5407:2: note: Loop condition is true. Entering loop body
for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) {
vim +/start_addr +2656 mm/page_alloc.c
c361be55b31284 Mel Gorman 2007-10-16 2649
253f456a5cb652 Mike Rapoport 2022-01-04 2650 static int set_pageblock_unmapped(struct zone *zone, struct page *page,
253f456a5cb652 Mike Rapoport 2022-01-04 2651 unsigned int order)
253f456a5cb652 Mike Rapoport 2022-01-04 2652 {
253f456a5cb652 Mike Rapoport 2022-01-04 2653 #ifdef CONFIG_ARCH_WANTS_GFP_UNMAPPED
253f456a5cb652 Mike Rapoport 2022-01-04 2654 unsigned long start_pfn = page_to_pfn(page) & ~(pageblock_nr_pages - 1);
253f456a5cb652 Mike Rapoport 2022-01-04 2655 unsigned long end_pfn = start_pfn + pageblock_nr_pages;
253f456a5cb652 Mike Rapoport 2022-01-04 @2656 unsigned long start_addr = PFN_PHYS(start_pfn);
253f456a5cb652 Mike Rapoport 2022-01-04 @2657 unsigned long end_addr = PFN_PHYS(end_pfn);
253f456a5cb652 Mike Rapoport 2022-01-04 2658 unsigned long pfn, err;
253f456a5cb652 Mike Rapoport 2022-01-04 2659
253f456a5cb652 Mike Rapoport 2022-01-04 2660 BUILD_BUG_ON(pageblock_order != PMD_ORDER);
253f456a5cb652 Mike Rapoport 2022-01-04 2661
253f456a5cb652 Mike Rapoport 2022-01-04 2662 if (is_migrate_unmapped_page(page))
253f456a5cb652 Mike Rapoport 2022-01-04 2663 return 0;
253f456a5cb652 Mike Rapoport 2022-01-04 2664
253f456a5cb652 Mike Rapoport 2022-01-04 2665 /*
253f456a5cb652 Mike Rapoport 2022-01-04 2666 * Calling set_direct_map_invalid_noflush() for the first page in a
253f456a5cb652 Mike Rapoport 2022-01-04 2667 * pageblock will split PMD entry and it may fail to allocat the
253f456a5cb652 Mike Rapoport 2022-01-04 2668 * PMD page. Subsequent calls will only update the PTEs, so they
253f456a5cb652 Mike Rapoport 2022-01-04 2669 * cannot fail.
253f456a5cb652 Mike Rapoport 2022-01-04 2670 */
253f456a5cb652 Mike Rapoport 2022-01-04 2671 err = set_direct_map_invalid_noflush(page);
253f456a5cb652 Mike Rapoport 2022-01-04 2672 if (err) {
253f456a5cb652 Mike Rapoport 2022-01-04 2673 int migratetype = get_pageblock_migratetype(page);
253f456a5cb652 Mike Rapoport 2022-01-04 2674
253f456a5cb652 Mike Rapoport 2022-01-04 2675 move_to_free_list(page, zone, order, migratetype);
253f456a5cb652 Mike Rapoport 2022-01-04 2676 return err;
253f456a5cb652 Mike Rapoport 2022-01-04 2677 }
253f456a5cb652 Mike Rapoport 2022-01-04 2678
253f456a5cb652 Mike Rapoport 2022-01-04 2679 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
253f456a5cb652 Mike Rapoport 2022-01-04 2680 page = pfn_to_page(pfn);
253f456a5cb652 Mike Rapoport 2022-01-04 2681 if (PageBuddy(page))
253f456a5cb652 Mike Rapoport 2022-01-04 2682 set_direct_map_invalid_noflush(page);
253f456a5cb652 Mike Rapoport 2022-01-04 2683 }
253f456a5cb652 Mike Rapoport 2022-01-04 2684
253f456a5cb652 Mike Rapoport 2022-01-04 2685 flush_tlb_kernel_range(start_addr, end_addr);
253f456a5cb652 Mike Rapoport 2022-01-04 2686 set_pageblock_migratetype(page, MIGRATE_UNMAPPED);
253f456a5cb652 Mike Rapoport 2022-01-04 2687 move_freepages_block(zone, page, MIGRATE_UNMAPPED, NULL);
253f456a5cb652 Mike Rapoport 2022-01-04 2688 #endif
253f456a5cb652 Mike Rapoport 2022-01-04 2689
253f456a5cb652 Mike Rapoport 2022-01-04 2690 return 0;
253f456a5cb652 Mike Rapoport 2022-01-04 2691 }
253f456a5cb652 Mike Rapoport 2022-01-04 2692
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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