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Message-ID: <ba7dea85-4bd4-42f7-be04-c23afff5b34b@nvidia.com>
Date: Tue, 3 Feb 2026 21:34:40 +1100
From: Balbir Singh <balbirs@...dia.com>
To: Dan Carpenter <dan.carpenter@...aro.org>, oe-kbuild@...ts.linux.dev,
Alistair Popple <apopple@...dia.com>
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
Linux Memory Management List <linux-mm@...ck.org>,
Björn Töpel <bjorn@...osinc.com>,
Jason Gunthorpe <jgg@...dia.com>
Subject: Re: lib/test_hmm.c:932 dmirror_migrate_to_system() error:
uninitialized symbol 'ret'.
On 1/18/26 23:04, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 944aacb68baf7624ab8d277d0ebf07f025ca137c
> commit: d438d273417055241ebaaf1ba3be23459fc27cba mm: remove devmap related functions and page table bits
> config: s390-randconfig-r071-20260115 (https://download.01.org/0day-ci/archive/20260115/202601152125.McLpiKxS-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
> 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/202601152125.McLpiKxS-lkp@intel.com/
>
> smatch warnings:
> lib/test_hmm.c:932 dmirror_migrate_to_system() error: uninitialized symbol 'ret'.
>
> vim +/ret +932 lib/test_hmm.c
>
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 875 static int dmirror_migrate_to_system(struct dmirror *dmirror,
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 876 struct hmm_dmirror_cmd *cmd)
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 877 {
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 878 unsigned long start, end, addr;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 879 unsigned long size = cmd->npages << PAGE_SHIFT;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 880 struct mm_struct *mm = dmirror->notifier.mm;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 881 struct vm_area_struct *vma;
> 6046a3bed1c2b02 Arnd Bergmann 2025-06-10 882 unsigned long src_pfns[32] = { 0 };
> 6046a3bed1c2b02 Arnd Bergmann 2025-06-10 883 unsigned long dst_pfns[32] = { 0 };
> 16ce101db85db69 Alistair Popple 2022-09-28 884 struct migrate_vma args = { 0 };
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 885 unsigned long next;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 886 int ret;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 887
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 888 start = cmd->addr;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 889 end = start + size;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 890 if (end < start)
>
> If end == start then ret is uninitialized.
>
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 891 return -EINVAL;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 892
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 893 /* Since the mm is for the mirrored process, get a reference first. */
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 894 if (!mmget_not_zero(mm))
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 895 return -EINVAL;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 896
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 897 cmd->cpages = 0;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 898 mmap_read_lock(mm);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 899 for (addr = start; addr < end; addr = next) {
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 900 vma = vma_lookup(mm, addr);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 901 if (!vma || !(vma->vm_flags & VM_READ)) {
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 902 ret = -EINVAL;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 903 goto out;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 904 }
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 905 next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT));
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 906 if (next > vma->vm_end)
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 907 next = vma->vm_end;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 908
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 909 args.vma = vma;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 910 args.src = src_pfns;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 911 args.dst = dst_pfns;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 912 args.start = addr;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 913 args.end = next;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 914 args.pgmap_owner = dmirror->mdevice;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 915 args.flags = dmirror_select_device(dmirror);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 916
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 917 ret = migrate_vma_setup(&args);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 918 if (ret)
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 919 goto out;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 920
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 921 pr_debug("Migrating from device mem to sys mem\n");
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 922 dmirror_devmem_fault_alloc_and_copy(&args, dmirror);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 923
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 924 migrate_vma_pages(&args);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 925 cmd->cpages += dmirror_successful_migrated_pages(&args);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 926 migrate_vma_finalize(&args);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 927 }
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 928 out:
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 929 mmap_read_unlock(mm);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 930 mmput(mm);
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 931
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 @932 return ret;
> 4c2e0f764eb4444 Alex Sierra 2022-07-15 933 }
>
The code looks older than the current top of master? The smatch warning is still valid though. I was wondering
did smatch get new heuristics to catch this?
Balbir
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