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References: <202302281802.J93Nma7q-lkp@intel.com>
In-Reply-To: <202302281802.J93Nma7q-lkp@intel.com>
From: Suren Baghdasaryan <surenb@google.com>
Date: Tue, 28 Feb 2023 10:04:49 -0800
Message-ID: <CAJuCfpHz3uECOuk6rRrV6Vn5r7+vn8HnC5cY7OZVHtGsAeE11A@mail.gmail.com>
Subject: Re: [ammarfaizi2-block:akpm/mm/mm-unstable 82/99] mm/mmap.c:516
vma_prepare() error: we previously assumed 'vp->vma' could be null (see line 505)
To: Dan Carpenter <error27@gmail.com>
Cc: oe-kbuild@lists.linux.dev, lkp@intel.com, oe-kbuild-all@lists.linux.dev,
Ammar Faizi <ammarfaizi2@gnuweeb.org>, "GNU/Weeb Mailing List" <gwml@vger.gnuweeb.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>
Content-Type: text/plain; charset="UTF-8"
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On Tue, Feb 28, 2023 at 6:24 AM Dan Carpenter <error27@gmail.com> wrote:
>
> tree: https://github.com/ammarfaizi2/linux-block akpm/mm/mm-unstable
> head: 61edd3b68c3185673c9b05dfe48038692964c73b
> commit: f517f7ae341d933856cdf4d9d773027681ed5dff [82/99] mm/mmap: write-lock VMAs in vma_prepare before modifying them
> config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20230228/202302281802.J93Nma7q-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <error27@gmail.com>
> | Link: https://lore.kernel.org/r/202302281802.J93Nma7q-lkp@intel.com/
Thanks for reporting!
>
> smatch warnings:
> mm/mmap.c:516 vma_prepare() error: we previously assumed 'vp->vma' could be null (see line 505)
>
> vim +516 mm/mmap.c
>
> 440703e082b9c7 Liam R. Howlett 2023-01-20 503 static inline void vma_prepare(struct vma_prepare *vp)
> 440703e082b9c7 Liam R. Howlett 2023-01-20 504 {
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 @505 if (vp->vma)
>
> Check presumes that vp->vma can be NULL. On my other system (with
> yesterday's linux-next code) vp->vma can never be NULL.
I think the check here is not needed since vp->vma should always be
non-NULL. I'll double-check and will remove it if that is confirmed.
Thanks,
Suren.
>
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 506 vma_start_write(vp->vma);
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 507 if (vp->adj_next)
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 508 vma_start_write(vp->adj_next);
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 509 /* vp->insert is always a newly created VMA, no need for locking */
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 510 if (vp->remove)
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 511 vma_start_write(vp->remove);
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 512 if (vp->remove2)
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 513 vma_start_write(vp->remove2);
> f517f7ae341d93 Suren Baghdasaryan 2023-02-27 514
> 440703e082b9c7 Liam R. Howlett 2023-01-20 515 if (vp->file) {
> 440703e082b9c7 Liam R. Howlett 2023-01-20 @516 uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
> ^^^^^^^
> Uncheck dereference.
>
> 440703e082b9c7 Liam R. Howlett 2023-01-20 517
> 440703e082b9c7 Liam R. Howlett 2023-01-20 518 if (vp->adj_next)
> 440703e082b9c7 Liam R. Howlett 2023-01-20 519 uprobe_munmap(vp->adj_next, vp->adj_next->vm_start,
> 440703e082b9c7 Liam R. Howlett 2023-01-20 520 vp->adj_next->vm_end);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 521
> 440703e082b9c7 Liam R. Howlett 2023-01-20 522 i_mmap_lock_write(vp->mapping);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 523 if (vp->insert && vp->insert->vm_file) {
> 440703e082b9c7 Liam R. Howlett 2023-01-20 524 /*
> 440703e082b9c7 Liam R. Howlett 2023-01-20 525 * Put into interval tree now, so instantiated pages
> 440703e082b9c7 Liam R. Howlett 2023-01-20 526 * are visible to arm/parisc __flush_dcache_page
> 440703e082b9c7 Liam R. Howlett 2023-01-20 527 * throughout; but we cannot insert into address
> 440703e082b9c7 Liam R. Howlett 2023-01-20 528 * space until vma start or end is updated.
> 440703e082b9c7 Liam R. Howlett 2023-01-20 529 */
> 440703e082b9c7 Liam R. Howlett 2023-01-20 530 __vma_link_file(vp->insert,
> 440703e082b9c7 Liam R. Howlett 2023-01-20 531 vp->insert->vm_file->f_mapping);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 532 }
> 440703e082b9c7 Liam R. Howlett 2023-01-20 533 }
> 440703e082b9c7 Liam R. Howlett 2023-01-20 534
> 440703e082b9c7 Liam R. Howlett 2023-01-20 535 if (vp->anon_vma) {
> 440703e082b9c7 Liam R. Howlett 2023-01-20 536 anon_vma_lock_write(vp->anon_vma);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 537 anon_vma_interval_tree_pre_update_vma(vp->vma);
>
> More unchecked dereferences.
>
> 440703e082b9c7 Liam R. Howlett 2023-01-20 538 if (vp->adj_next)
> 440703e082b9c7 Liam R. Howlett 2023-01-20 539 anon_vma_interval_tree_pre_update_vma(vp->adj_next);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 540 }
> 440703e082b9c7 Liam R. Howlett 2023-01-20 541
> 440703e082b9c7 Liam R. Howlett 2023-01-20 542 if (vp->file) {
> 440703e082b9c7 Liam R. Howlett 2023-01-20 543 flush_dcache_mmap_lock(vp->mapping);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 544 vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 545 if (vp->adj_next)
> 440703e082b9c7 Liam R. Howlett 2023-01-20 546 vma_interval_tree_remove(vp->adj_next,
> 440703e082b9c7 Liam R. Howlett 2023-01-20 547 &vp->mapping->i_mmap);
> 440703e082b9c7 Liam R. Howlett 2023-01-20 548 }
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests
>