| Message ID | 20221223155616.297723-3-david@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: uffd-wp + change_protection() cleanups | expand |
Hi David,
I love your patch! Yet something to improve:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/David-Hildenbrand/mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range/20221224-000206
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20221223155616.297723-3-david%40redhat.com
patch subject: [PATCH v1 2/2] mm/mprotect: drop pgprot_t parameter from change_protection()
config: mips-malta_defconfig
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project f5700e7b69048de958172fb513b336564e7f8709)
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 mips cross compiling tool for clang build
# apt-get install binutils-mipsel-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/c77a6bee317925cf3d078bc97a42d644503b9f1a
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review David-Hildenbrand/mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range/20221224-000206
git checkout c77a6bee317925cf3d078bc97a42d644503b9f1a
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
>> mm/mprotect.c:523:13: error: use of undeclared identifier 'PAGE_NONE'
newprot = PAGE_NONE;
^
1 error generated.
vim +/PAGE_NONE +523 mm/mprotect.c
507
508 unsigned long change_protection(struct mmu_gather *tlb,
509 struct vm_area_struct *vma, unsigned long start,
510 unsigned long end, unsigned long cp_flags)
511 {
512 pgprot_t newprot = vma->vm_page_prot;
513 unsigned long pages;
514
515 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
516
517 /*
518 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
519 * are expected to reflect their requirements via VMA flags such that
520 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
521 */
522 if (cp_flags & MM_CP_PROT_NUMA)
> 523 newprot = PAGE_NONE;
524
525 if (is_vm_hugetlb_page(vma))
526 pages = hugetlb_change_protection(vma, start, end, newprot,
527 cp_flags);
528 else
529 pages = change_protection_range(tlb, vma, start, end, newprot,
530 cp_flags);
531
532 return pages;
533 }
534
Hi David,
I love your patch! Yet something to improve:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/David-Hildenbrand/mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range/20221224-000206
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20221223155616.297723-3-david%40redhat.com
patch subject: [PATCH v1 2/2] mm/mprotect: drop pgprot_t parameter from change_protection()
config: arc-tb10x_defconfig
compiler: arc-elf-gcc (GCC) 12.1.0
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://github.com/intel-lab-lkp/linux/commit/c77a6bee317925cf3d078bc97a42d644503b9f1a
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review David-Hildenbrand/mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range/20221224-000206
git checkout c77a6bee317925cf3d078bc97a42d644503b9f1a
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
mm/mprotect.c: In function 'change_protection':
>> mm/mprotect.c:523:27: error: 'PAGE_NONE' undeclared (first use in this function); did you mean 'PAGE_U_NONE'?
523 | newprot = PAGE_NONE;
| ^~~~~~~~~
| PAGE_U_NONE
mm/mprotect.c:523:27: note: each undeclared identifier is reported only once for each function it appears in
vim +523 mm/mprotect.c
507
508 unsigned long change_protection(struct mmu_gather *tlb,
509 struct vm_area_struct *vma, unsigned long start,
510 unsigned long end, unsigned long cp_flags)
511 {
512 pgprot_t newprot = vma->vm_page_prot;
513 unsigned long pages;
514
515 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
516
517 /*
518 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
519 * are expected to reflect their requirements via VMA flags such that
520 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
521 */
522 if (cp_flags & MM_CP_PROT_NUMA)
> 523 newprot = PAGE_NONE;
524
525 if (is_vm_hugetlb_page(vma))
526 pages = hugetlb_change_protection(vma, start, end, newprot,
527 cp_flags);
528 else
529 pages = change_protection_range(tlb, vma, start, end, newprot,
530 cp_flags);
531
532 return pages;
533 }
534
On 23.12.22 16:56, David Hildenbrand wrote: > Being able to provide a custom protection opens the door for > inconsistencies and BUGs: for example, accidentally allowing for more > permissions than desired by other mechanisms (e.g., softdirty tracking). > vma->vm_page_prot should be the single source of truth. > > Only PROT_NUMA is special: there is no way we can erroneously allow > for more permissions when removing all permissions. Special-case using > the MM_CP_PROT_NUMA flag. > > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > include/linux/mm.h | 3 +-- > mm/mempolicy.c | 3 +-- > mm/mprotect.c | 14 +++++++++++--- > mm/userfaultfd.c | 3 +-- > 4 files changed, 14 insertions(+), 9 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index f3f196e4d66d..b8be8c33ca20 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2148,8 +2148,7 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, > pte_t pte); > extern unsigned long change_protection(struct mmu_gather *tlb, > struct vm_area_struct *vma, unsigned long start, > - unsigned long end, pgprot_t newprot, > - unsigned long cp_flags); > + unsigned long end, unsigned long cp_flags); > extern int mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, > struct vm_area_struct **pprev, unsigned long start, > unsigned long end, unsigned long newflags); > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 61aa9aedb728..c3f02703a710 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -635,8 +635,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma, > > tlb_gather_mmu(&tlb, vma->vm_mm); > > - nr_updated = change_protection(&tlb, vma, addr, end, PAGE_NONE, > - MM_CP_PROT_NUMA); > + nr_updated = change_protection(&tlb, vma, addr, end, MM_CP_PROT_NUMA); > if (nr_updated) > count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated); > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 908df12caa26..569cefa668a6 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -503,13 +503,21 @@ static unsigned long change_protection_range(struct mmu_gather *tlb, > > unsigned long change_protection(struct mmu_gather *tlb, > struct vm_area_struct *vma, unsigned long start, > - unsigned long end, pgprot_t newprot, > - unsigned long cp_flags) > + unsigned long end, unsigned long cp_flags) > { > + pgprot_t newprot = vma->vm_page_prot; > unsigned long pages; > > BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); > > + /* > + * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) > + * are expected to reflect their requirements via VMA flags such that > + * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. > + */ > + if (cp_flags & MM_CP_PROT_NUMA) > + newprot = PAGE_NONE; > + > if (is_vm_hugetlb_page(vma)) > pages = hugetlb_change_protection(vma, start, end, newprot, > cp_flags); > @@ -638,7 +646,7 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, > mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; > vma_set_page_prot(vma); > > - change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags); > + change_protection(tlb, vma, start, end, mm_cp_flags); > > /* > * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index 351e8d6b398b..be7ee9d82e72 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -744,8 +744,7 @@ void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, > if (vma_wants_manual_pte_write_upgrade(dst_vma)) > mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; > tlb_gather_mmu(&tlb, dst_mm); > - change_protection(&tlb, dst_vma, start, start + len, vma->vm_page_prot, > - mm_cp_flags); > + change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags); > tlb_finish_mmu(&tlb); > } > The following fix for compilation errors without PAGE_NONE: From a164d6cf728e353294aa9e65b8ead5241c800421 Mon Sep 17 00:00:00 2001 From: David Hildenbrand <david@redhat.com> Date: Sat, 24 Dec 2022 15:01:18 +0100 Subject: [PATCH] fixup: mm/mprotect: drop pgprot_t parameter from change_protection() PAGE_NONE might not be defined without CONFIG_NUMA_BALANCING Signed-off-by: David Hildenbrand <david@redhat.com> --- mm/mprotect.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/mprotect.c b/mm/mprotect.c index 569cefa668a6..809832954898 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -510,6 +510,7 @@ unsigned long change_protection(struct mmu_gather *tlb, BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); +#ifdef CONFIG_NUMA_BALANCING /* * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) * are expected to reflect their requirements via VMA flags such that @@ -517,6 +518,9 @@ unsigned long change_protection(struct mmu_gather *tlb, */ if (cp_flags & MM_CP_PROT_NUMA) newprot = PAGE_NONE; +#else + WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); +#endif if (is_vm_hugetlb_page(vma)) pages = hugetlb_change_protection(vma, start, end, newprot,
diff --git a/include/linux/mm.h b/include/linux/mm.h index f3f196e4d66d..b8be8c33ca20 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2148,8 +2148,7 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, pte_t pte); extern unsigned long change_protection(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, - unsigned long end, pgprot_t newprot, - unsigned long cp_flags); + unsigned long end, unsigned long cp_flags); extern int mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long start, unsigned long end, unsigned long newflags); diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 61aa9aedb728..c3f02703a710 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -635,8 +635,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma, tlb_gather_mmu(&tlb, vma->vm_mm); - nr_updated = change_protection(&tlb, vma, addr, end, PAGE_NONE, - MM_CP_PROT_NUMA); + nr_updated = change_protection(&tlb, vma, addr, end, MM_CP_PROT_NUMA); if (nr_updated) count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated); diff --git a/mm/mprotect.c b/mm/mprotect.c index 908df12caa26..569cefa668a6 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -503,13 +503,21 @@ static unsigned long change_protection_range(struct mmu_gather *tlb, unsigned long change_protection(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, - unsigned long end, pgprot_t newprot, - unsigned long cp_flags) + unsigned long end, unsigned long cp_flags) { + pgprot_t newprot = vma->vm_page_prot; unsigned long pages; BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); + /* + * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) + * are expected to reflect their requirements via VMA flags such that + * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. + */ + if (cp_flags & MM_CP_PROT_NUMA) + newprot = PAGE_NONE; + if (is_vm_hugetlb_page(vma)) pages = hugetlb_change_protection(vma, start, end, newprot, cp_flags); @@ -638,7 +646,7 @@ mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; vma_set_page_prot(vma); - change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags); + change_protection(tlb, vma, start, end, mm_cp_flags); /* * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 351e8d6b398b..be7ee9d82e72 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -744,8 +744,7 @@ void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, if (vma_wants_manual_pte_write_upgrade(dst_vma)) mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; tlb_gather_mmu(&tlb, dst_mm); - change_protection(&tlb, dst_vma, start, start + len, vma->vm_page_prot, - mm_cp_flags); + change_protection(&tlb, dst_vma, start, start + len, mm_cp_flags); tlb_finish_mmu(&tlb); }
Being able to provide a custom protection opens the door for inconsistencies and BUGs: for example, accidentally allowing for more permissions than desired by other mechanisms (e.g., softdirty tracking). vma->vm_page_prot should be the single source of truth. Only PROT_NUMA is special: there is no way we can erroneously allow for more permissions when removing all permissions. Special-case using the MM_CP_PROT_NUMA flag. Signed-off-by: David Hildenbrand <david@redhat.com> --- include/linux/mm.h | 3 +-- mm/mempolicy.c | 3 +-- mm/mprotect.c | 14 +++++++++++--- mm/userfaultfd.c | 3 +-- 4 files changed, 14 insertions(+), 9 deletions(-)