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Message-ID: <202601200251.uRdWeQPq-lkp@intel.com>
Date: Tue, 20 Jan 2026 09:29:55 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: oe-kbuild@...ts.linux.dev, mpenttil@...hat.com, linux-mm@...ck.org
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
linux-kernel@...r.kernel.org,
Mika Penttilä <mpenttil@...hat.com>,
David Hildenbrand <david@...hat.com>,
Jason Gunthorpe <jgg@...dia.com>,
Leon Romanovsky <leonro@...dia.com>,
Alistair Popple <apopple@...dia.com>,
Balbir Singh <balbirs@...dia.com>, Zi Yan <ziy@...dia.com>,
Matthew Brost <matthew.brost@...el.com>
Subject: Re: [PATCH v2 1/3] mm: unified hmm fault and migrate device pagewalk
paths
Hi,
kernel test robot noticed the following build warnings:
url: https://github.com/intel-lab-lkp/linux/commits/mpenttil-redhat-com/mm-unified-hmm-fault-and-migrate-device-pagewalk-paths/20260119-193100
base: 24d479d26b25bce5faea3ddd9fa8f3a6c3129ea7
patch link: https://lore.kernel.org/r/20260119112502.645059-2-mpenttil%40redhat.com
patch subject: [PATCH v2 1/3] mm: unified hmm fault and migrate device pagewalk paths
config: sparc-randconfig-r071-20260119 (https://download.01.org/0day-ci/archive/20260120/202601200251.uRdWeQPq-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 15.2.0
smatch version: v0.5.0-8985-g2614ff1a
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@...el.com>
| Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
| Closes: https://lore.kernel.org/r/202601200251.uRdWeQPq-lkp@intel.com/
smatch warnings:
mm/hmm.c:960 hmm_vma_walk_pmd() warn: missing error code? 'r'
mm/hmm.c:1310 hmm_range_fault() error: we previously assumed 'range->notifier' could be null (see line 1296)
vim +/r +960 mm/hmm.c
53f5c3f489ecdd Jérôme Glisse 2018-04-10 926 static int hmm_vma_walk_pmd(pmd_t *pmdp,
53f5c3f489ecdd Jérôme Glisse 2018-04-10 927 unsigned long start,
53f5c3f489ecdd Jérôme Glisse 2018-04-10 928 unsigned long end,
53f5c3f489ecdd Jérôme Glisse 2018-04-10 929 struct mm_walk *walk)
53f5c3f489ecdd Jérôme Glisse 2018-04-10 930 {
53f5c3f489ecdd Jérôme Glisse 2018-04-10 931 struct hmm_vma_walk *hmm_vma_walk = walk->private;
53f5c3f489ecdd Jérôme Glisse 2018-04-10 932 struct hmm_range *range = hmm_vma_walk->range;
2733ea144dcce7 Jason Gunthorpe 2020-05-01 933 unsigned long *hmm_pfns =
2733ea144dcce7 Jason Gunthorpe 2020-05-01 934 &range->hmm_pfns[(start - range->start) >> PAGE_SHIFT];
2288a9a68175ce Jason Gunthorpe 2020-03-05 935 unsigned long npages = (end - start) >> PAGE_SHIFT;
adc5de78797562 Mika Penttilä 2026-01-19 936 struct mm_struct *mm = walk->vma->vm_mm;
2288a9a68175ce Jason Gunthorpe 2020-03-05 937 unsigned long addr = start;
adc5de78797562 Mika Penttilä 2026-01-19 938 enum migrate_vma_info minfo;
adc5de78797562 Mika Penttilä 2026-01-19 939 unsigned long i;
adc5de78797562 Mika Penttilä 2026-01-19 940 spinlock_t *ptl;
53f5c3f489ecdd Jérôme Glisse 2018-04-10 941 pte_t *ptep;
d08faca018c461 Jérôme Glisse 2018-10-30 942 pmd_t pmd;
adc5de78797562 Mika Penttilä 2026-01-19 943 int r;
adc5de78797562 Mika Penttilä 2026-01-19 944
adc5de78797562 Mika Penttilä 2026-01-19 945 minfo = hmm_select_migrate(range);
53f5c3f489ecdd Jérôme Glisse 2018-04-10 946
53f5c3f489ecdd Jérôme Glisse 2018-04-10 947 again:
adc5de78797562 Mika Penttilä 2026-01-19 948 hmm_vma_walk->locked = false;
adc5de78797562 Mika Penttilä 2026-01-19 949 hmm_vma_walk->pmdlocked = false;
26e1a0c3277d7f Hugh Dickins 2023-06-08 950 pmd = pmdp_get_lockless(pmdp);
adc5de78797562 Mika Penttilä 2026-01-19 951 if (pmd_none(pmd)) {
adc5de78797562 Mika Penttilä 2026-01-19 952 r = hmm_vma_walk_hole(start, end, -1, walk);
adc5de78797562 Mika Penttilä 2026-01-19 953 if (r || !minfo)
adc5de78797562 Mika Penttilä 2026-01-19 954 return r;
if minfo is NULL do we return success?
adc5de78797562 Mika Penttilä 2026-01-19 955
adc5de78797562 Mika Penttilä 2026-01-19 956 ptl = pmd_lock(walk->mm, pmdp);
adc5de78797562 Mika Penttilä 2026-01-19 957 if (pmd_none(*pmdp)) {
adc5de78797562 Mika Penttilä 2026-01-19 958 // hmm_vma_walk_hole() filled migration needs
adc5de78797562 Mika Penttilä 2026-01-19 959 spin_unlock(ptl);
adc5de78797562 Mika Penttilä 2026-01-19 @960 return r;
And here?
adc5de78797562 Mika Penttilä 2026-01-19 961 }
adc5de78797562 Mika Penttilä 2026-01-19 962 spin_unlock(ptl);
adc5de78797562 Mika Penttilä 2026-01-19 963 }
53f5c3f489ecdd Jérôme Glisse 2018-04-10 964
0ac881efe16468 Lorenzo Stoakes 2025-11-10 965 if (thp_migration_supported() && pmd_is_migration_entry(pmd)) {
adc5de78797562 Mika Penttilä 2026-01-19 966 if (!minfo) {
2733ea144dcce7 Jason Gunthorpe 2020-05-01 967 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0)) {
d08faca018c461 Jérôme Glisse 2018-10-30 968 hmm_vma_walk->last = addr;
d2e8d551165ccb Ralph Campbell 2019-07-25 969 pmd_migration_entry_wait(walk->mm, pmdp);
73231612dc7c90 Jérôme Glisse 2019-05-13 970 return -EBUSY;
d08faca018c461 Jérôme Glisse 2018-10-30 971 }
2288a9a68175ce Jason Gunthorpe 2020-03-05 972 }
adc5de78797562 Mika Penttilä 2026-01-19 973 for (i = 0; addr < end; addr += PAGE_SIZE, i++)
adc5de78797562 Mika Penttilä 2026-01-19 974 hmm_pfns[i] &= HMM_PFN_INOUT_FLAGS;
2288a9a68175ce Jason Gunthorpe 2020-03-05 975
adc5de78797562 Mika Penttilä 2026-01-19 976 return 0;
adc5de78797562 Mika Penttilä 2026-01-19 977 }
adc5de78797562 Mika Penttilä 2026-01-19 978
adc5de78797562 Mika Penttilä 2026-01-19 979 if (minfo) {
adc5de78797562 Mika Penttilä 2026-01-19 980 hmm_vma_walk->ptl = pmd_lock(mm, pmdp);
adc5de78797562 Mika Penttilä 2026-01-19 981 hmm_vma_walk->pmdlocked = true;
adc5de78797562 Mika Penttilä 2026-01-19 982 pmd = pmdp_get(pmdp);
adc5de78797562 Mika Penttilä 2026-01-19 983 } else
adc5de78797562 Mika Penttilä 2026-01-19 984 pmd = pmdp_get_lockless(pmdp);
adc5de78797562 Mika Penttilä 2026-01-19 985
adc5de78797562 Mika Penttilä 2026-01-19 986 if (pmd_trans_huge(pmd) || !pmd_present(pmd)) {
adc5de78797562 Mika Penttilä 2026-01-19 987
adc5de78797562 Mika Penttilä 2026-01-19 988 if (!pmd_present(pmd)) {
adc5de78797562 Mika Penttilä 2026-01-19 989 r = hmm_vma_handle_absent_pmd(walk, start, end, hmm_pfns,
10b9feee2d0dc8 Francois Dugast 2025-09-08 990 pmd);
adc5de78797562 Mika Penttilä 2026-01-19 991 if (r || !minfo)
adc5de78797562 Mika Penttilä 2026-01-19 992 return r;
Same
adc5de78797562 Mika Penttilä 2026-01-19 993 } else {
d08faca018c461 Jérôme Glisse 2018-10-30 994
53f5c3f489ecdd Jérôme Glisse 2018-04-10 995 /*
adc5de78797562 Mika Penttilä 2026-01-19 996 * No need to take pmd_lock here if not migrating,
adc5de78797562 Mika Penttilä 2026-01-19 997 * even if some other thread is splitting the huge
adc5de78797562 Mika Penttilä 2026-01-19 998 * pmd we will get that event through mmu_notifier callback.
53f5c3f489ecdd Jérôme Glisse 2018-04-10 999 *
d2e8d551165ccb Ralph Campbell 2019-07-25 1000 * So just read pmd value and check again it's a transparent
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1001 * huge or device mapping one and compute corresponding pfn
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1002 * values.
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1003 */
adc5de78797562 Mika Penttilä 2026-01-19 1004
adc5de78797562 Mika Penttilä 2026-01-19 1005 if (!pmd_trans_huge(pmd)) {
adc5de78797562 Mika Penttilä 2026-01-19 1006 // must be lockless
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1007 goto again;
adc5de78797562 Mika Penttilä 2026-01-19 1008 }
adc5de78797562 Mika Penttilä 2026-01-19 1009
adc5de78797562 Mika Penttilä 2026-01-19 1010 r = hmm_vma_handle_pmd(walk, addr, end, hmm_pfns, pmd);
adc5de78797562 Mika Penttilä 2026-01-19 1011
adc5de78797562 Mika Penttilä 2026-01-19 1012 if (r || !minfo)
adc5de78797562 Mika Penttilä 2026-01-19 1013 return r;
Same?
adc5de78797562 Mika Penttilä 2026-01-19 1014 }
adc5de78797562 Mika Penttilä 2026-01-19 1015
adc5de78797562 Mika Penttilä 2026-01-19 1016 r = hmm_vma_handle_migrate_prepare_pmd(walk, pmdp, start, end, hmm_pfns);
adc5de78797562 Mika Penttilä 2026-01-19 1017
adc5de78797562 Mika Penttilä 2026-01-19 1018 if (hmm_vma_walk->pmdlocked) {
adc5de78797562 Mika Penttilä 2026-01-19 1019 spin_unlock(hmm_vma_walk->ptl);
adc5de78797562 Mika Penttilä 2026-01-19 1020 hmm_vma_walk->pmdlocked = false;
adc5de78797562 Mika Penttilä 2026-01-19 1021 }
adc5de78797562 Mika Penttilä 2026-01-19 1022
adc5de78797562 Mika Penttilä 2026-01-19 1023 if (r == -ENOENT) {
adc5de78797562 Mika Penttilä 2026-01-19 1024 r = hmm_vma_walk_split(pmdp, addr, walk);
adc5de78797562 Mika Penttilä 2026-01-19 1025 if (r) {
adc5de78797562 Mika Penttilä 2026-01-19 1026 /* Split not successful, skip */
adc5de78797562 Mika Penttilä 2026-01-19 1027 return hmm_pfns_fill(start, end, hmm_vma_walk, HMM_PFN_ERROR);
adc5de78797562 Mika Penttilä 2026-01-19 1028 }
adc5de78797562 Mika Penttilä 2026-01-19 1029
adc5de78797562 Mika Penttilä 2026-01-19 1030 /* Split successful or "again", reloop */
adc5de78797562 Mika Penttilä 2026-01-19 1031 hmm_vma_walk->last = addr;
adc5de78797562 Mika Penttilä 2026-01-19 1032 return -EBUSY;
adc5de78797562 Mika Penttilä 2026-01-19 1033 }
adc5de78797562 Mika Penttilä 2026-01-19 1034
adc5de78797562 Mika Penttilä 2026-01-19 1035 return r;
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1036
adc5de78797562 Mika Penttilä 2026-01-19 1037 }
adc5de78797562 Mika Penttilä 2026-01-19 1038
adc5de78797562 Mika Penttilä 2026-01-19 1039 if (hmm_vma_walk->pmdlocked) {
adc5de78797562 Mika Penttilä 2026-01-19 1040 spin_unlock(hmm_vma_walk->ptl);
adc5de78797562 Mika Penttilä 2026-01-19 1041 hmm_vma_walk->pmdlocked = false;
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1042 }
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1043
d08faca018c461 Jérôme Glisse 2018-10-30 1044 /*
d2e8d551165ccb Ralph Campbell 2019-07-25 1045 * We have handled all the valid cases above ie either none, migration,
d08faca018c461 Jérôme Glisse 2018-10-30 1046 * huge or transparent huge. At this point either it is a valid pmd
d08faca018c461 Jérôme Glisse 2018-10-30 1047 * entry pointing to pte directory or it is a bad pmd that will not
d08faca018c461 Jérôme Glisse 2018-10-30 1048 * recover.
d08faca018c461 Jérôme Glisse 2018-10-30 1049 */
2288a9a68175ce Jason Gunthorpe 2020-03-05 1050 if (pmd_bad(pmd)) {
2733ea144dcce7 Jason Gunthorpe 2020-05-01 1051 if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
2288a9a68175ce Jason Gunthorpe 2020-03-05 1052 return -EFAULT;
adc5de78797562 Mika Penttilä 2026-01-19 1053 return hmm_pfns_fill(start, end, hmm_vma_walk, HMM_PFN_ERROR);
2288a9a68175ce Jason Gunthorpe 2020-03-05 1054 }
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1055
adc5de78797562 Mika Penttilä 2026-01-19 1056 if (minfo) {
adc5de78797562 Mika Penttilä 2026-01-19 1057 ptep = pte_offset_map_lock(mm, pmdp, addr, &hmm_vma_walk->ptl);
adc5de78797562 Mika Penttilä 2026-01-19 1058 if (ptep)
adc5de78797562 Mika Penttilä 2026-01-19 1059 hmm_vma_walk->locked = true;
adc5de78797562 Mika Penttilä 2026-01-19 1060 } else
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1061 ptep = pte_offset_map(pmdp, addr);
6ec1905f6ec7f9 Hugh Dickins 2023-06-08 1062 if (!ptep)
6ec1905f6ec7f9 Hugh Dickins 2023-06-08 1063 goto again;
adc5de78797562 Mika Penttilä 2026-01-19 1064
2733ea144dcce7 Jason Gunthorpe 2020-05-01 1065 for (; addr < end; addr += PAGE_SIZE, ptep++, hmm_pfns++) {
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1066
2733ea144dcce7 Jason Gunthorpe 2020-05-01 1067 r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, hmm_pfns);
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1068 if (r) {
dfdc22078f3f06 Jason Gunthorpe 2020-02-28 1069 /* hmm_vma_handle_pte() did pte_unmap() */
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1070 return r;
53f5c3f489ecdd Jérôme Glisse 2018-04-10 1071 }
adc5de78797562 Mika Penttilä 2026-01-19 1072
adc5de78797562 Mika Penttilä 2026-01-19 1073 r = hmm_vma_handle_migrate_prepare(walk, pmdp, ptep, addr, hmm_pfns);
adc5de78797562 Mika Penttilä 2026-01-19 1074 if (r == -EAGAIN) {
adc5de78797562 Mika Penttilä 2026-01-19 1075 goto again;
adc5de78797562 Mika Penttilä 2026-01-19 1076 }
adc5de78797562 Mika Penttilä 2026-01-19 1077 if (r) {
adc5de78797562 Mika Penttilä 2026-01-19 1078 hmm_pfns_fill(addr, end, hmm_vma_walk, HMM_PFN_ERROR);
adc5de78797562 Mika Penttilä 2026-01-19 1079 break;
da4c3c735ea4dc Jérôme Glisse 2017-09-08 1080 }
adc5de78797562 Mika Penttilä 2026-01-19 1081 }
adc5de78797562 Mika Penttilä 2026-01-19 1082
adc5de78797562 Mika Penttilä 2026-01-19 1083 if (hmm_vma_walk->locked)
adc5de78797562 Mika Penttilä 2026-01-19 1084 pte_unmap_unlock(ptep - 1, hmm_vma_walk->ptl);
adc5de78797562 Mika Penttilä 2026-01-19 1085 else
da4c3c735ea4dc Jérôme Glisse 2017-09-08 1086 pte_unmap(ptep - 1);
adc5de78797562 Mika Penttilä 2026-01-19 1087
da4c3c735ea4dc Jérôme Glisse 2017-09-08 1088 return 0;
da4c3c735ea4dc Jérôme Glisse 2017-09-08 1089 }
--
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