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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 70D9580002 X-Stat-Signature: ar96xssdyc4tqbm6gbyz3cap5f9fuk1u X-Rspam-User: X-HE-Tag: 1757666476-569588 X-HE-Meta: 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 HVOp+qM+ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: [...] >>> +/* >>> + * We should remove the VM_SOFTDIRTY flag if the soft-dirty bit is >>> + * unavailable on which the kernel is running, even if the architecture >>> + * provides the resource and soft-dirty is compiled in. >>> + */ >>> +#ifdef CONFIG_MEM_SOFT_DIRTY >>> + if (!pgtable_soft_dirty_supported()) >>> + mnemonics[ilog2(VM_SOFTDIRTY)][0] = 0; >>> +#endif >> >> You can now drop the ifdef. > > Ok, you mean define VM_SOFTDIRTY 0x08000000 no matter if > MEM_SOFT_DIRTY is compiled in, right? > > Then I need memcpy() to set mnemonics[ilog2(VM_SOFTDIRTY)] here. The whole hunk will not be required when we make sure VM_SOFTDIRTY never gets set, correct? > >> >> But, I wonder if could we instead just stop setting the flag. Then we don't >> have to worry about any VM_SOFTDIRTY checks. >> >> Something like the following >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 892fe5dbf9de0..8b8bf63a32ef7 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -783,6 +783,7 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm) >> static inline void vm_flags_init(struct vm_area_struct *vma, >> vm_flags_t flags) >> { >> + VM_WARN_ON_ONCE(!pgtable_soft_dirty_supported() && (flags & VM_SOFTDIRTY)); >> ACCESS_PRIVATE(vma, __vm_flags) = flags; >> } >> >> @@ -801,6 +802,7 @@ static inline void vm_flags_reset(struct vm_area_struct *vma, >> static inline void vm_flags_reset_once(struct vm_area_struct *vma, >> vm_flags_t flags) >> { >> + VM_WARN_ON_ONCE(!pgtable_soft_dirty_supported() && (flags & VM_SOFTDIRTY)); >> vma_assert_write_locked(vma); >> WRITE_ONCE(ACCESS_PRIVATE(vma, __vm_flags), flags); >> } >> @@ -808,6 +810,7 @@ static inline void vm_flags_reset_once(struct vm_area_struct *vma, >> static inline void vm_flags_set(struct vm_area_struct *vma, >> vm_flags_t flags) >> { >> + VM_WARN_ON_ONCE(!pgtable_soft_dirty_supported() && (flags & VM_SOFTDIRTY)); >> vma_start_write(vma); >> ACCESS_PRIVATE(vma, __vm_flags) |= flags; >> } >> diff --git a/mm/mmap.c b/mm/mmap.c >> index 5fd3b80fda1d5..40cb3fbf9a247 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -1451,8 +1451,10 @@ static struct vm_area_struct *__install_special_mapping( >> return ERR_PTR(-ENOMEM); >> >> vma_set_range(vma, addr, addr + len, 0); >> - vm_flags_init(vma, (vm_flags | mm->def_flags | >> - VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK); >> + vm_flags |= mm->def_flags | VM_DONTEXPAND; > > Why use '|=' rather than not directly setting vm_flags which is an > uninitialized variable? vm_flags is passed in by the caller? But just to clarify: this code was just a quick hack, adjust it as you need. [...] >>> >>> + if (!pgtable_soft_dirty_supported()) >>> + return; >>> + >>> if (pmd_present(pmd)) { >>> /* See comment in change_huge_pmd() */ >>> old = pmdp_invalidate(vma, addr, pmdp); >> >> That would all be handled with the above never-set-VM_SOFTDIRTY. I meant that there is no need to add the pgtable_soft_dirty_supported() check. > > Sorry I'm not sure I understand here, you mean no longer need #ifdef > CONFIG_MEM_SOFT_DIRTY for these function definitions, right? Likely we could drop them. VM_SOFTDIRTY will never be set so the code will not be invoked. And for architectures where VM_SOFTDIRTY is never even possible (!CONFIG_MEM_SOFT_DIRTY) we keep it as 0. That way, the compiler can even optimize out all of that code because "vma->vm_flags & VM_SOFTDIRTY" -> "vma->vm_flags & 0" will never be true. > >> >>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h >>> index 4c035637eeb7..2a3578a4ae4c 100644 >>> --- a/include/linux/pgtable.h >>> +++ b/include/linux/pgtable.h >>> @@ -1537,6 +1537,18 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) >>> #define arch_start_context_switch(prev) do {} while (0) >>> #endif >>> >>> +/* >>> + * Some platforms can customize the PTE soft-dirty bit making it unavailable >>> + * even if the architecture provides the resource. >>> + * Adding this API allows architectures to add their own checks for the >>> + * devices on which the kernel is running. >>> + * Note: When overiding it, please make sure the CONFIG_MEM_SOFT_DIRTY >>> + * is part of this macro. >>> + */ >>> +#ifndef pgtable_soft_dirty_supported >>> +#define pgtable_soft_dirty_supported() IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) >>> +#endif >>> + >>> #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY >>> #ifndef CONFIG_ARCH_ENABLE_THP_MIGRATION >>> static inline pmd_t pmd_swp_mksoft_dirty(pmd_t pmd) >>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >>> index 830107b6dd08..b32ce2b0b998 100644 >>> --- a/mm/debug_vm_pgtable.c >>> +++ b/mm/debug_vm_pgtable.c >>> @@ -690,7 +690,7 @@ static void __init pte_soft_dirty_tests(struct pgtable_debug_args *args) >>> { >>> pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot); >>> >>> - if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)) >>> + if (!pgtable_soft_dirty_supported()) >>> return; >>> >>> pr_debug("Validating PTE soft dirty\n"); >>> @@ -702,7 +702,7 @@ static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *args) >>> { >>> pte_t pte; >>> >>> - if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)) >>> + if (!pgtable_soft_dirty_supported()) >>> return; >>> >>> pr_debug("Validating PTE swap soft dirty\n"); >>> @@ -718,7 +718,7 @@ static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args) >>> { >>> pmd_t pmd; >>> >>> - if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)) >>> + if (!pgtable_soft_dirty_supported()) >>> return; >>> >>> if (!has_transparent_hugepage()) >>> @@ -734,8 +734,8 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) >>> { >>> pmd_t pmd; >>> >>> - if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) || >>> - !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION)) >>> + if (!pgtable_soft_dirty_supported() || >>> + !IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION)) >>> return; >>> >>> if (!has_transparent_hugepage()) >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index 9c38a95e9f09..218d430a2ec6 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -2271,12 +2271,13 @@ static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, >>> >>> static pmd_t move_soft_dirty_pmd(pmd_t pmd) >>> { >>> -#ifdef CONFIG_MEM_SOFT_DIRTY >>> - if (unlikely(is_pmd_migration_entry(pmd))) >>> - pmd = pmd_swp_mksoft_dirty(pmd); >>> - else if (pmd_present(pmd)) >>> - pmd = pmd_mksoft_dirty(pmd); >>> -#endif >>> + if (pgtable_soft_dirty_supported()) { >>> + if (unlikely(is_pmd_migration_entry(pmd))) >>> + pmd = pmd_swp_mksoft_dirty(pmd); >>> + else if (pmd_present(pmd)) >>> + pmd = pmd_mksoft_dirty(pmd); >>> + } >>> + >> >> Wondering, should simply the arch take care of that and we can just clal >> pmd_swp_mksoft_dirty / pmd_mksoft_dirty? > I think we have that already in include/linux/pgtable.h: We have stubs that just don't do anything. For riscv support you would handle runtime-enablement in these helpers. > >> >>> return pmd; >>> } >>> >>> diff --git a/mm/internal.h b/mm/internal.h >>> index 45b725c3dc03..c6ca62f8ecf3 100644 >>> --- a/mm/internal.h >>> +++ b/mm/internal.h >>> @@ -1538,7 +1538,7 @@ static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma) >>> * VM_SOFTDIRTY is defined as 0x0, then !(vm_flags & VM_SOFTDIRTY) >>> * will be constantly true. >>> */ >>> - if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)) >>> + if (!pgtable_soft_dirty_supported()) >>> return false; >>> >> >> That should be handled with the above never-set-VM_SOFTDIRTY. > > We don't need to check if (!pgtable_soft_dirty_supported()) if I > understand correctly. Hm, let me think about that. No, I think this has to stay as the comment says, so this case here is special. -- Cheers David / dhildenb