Re: [PATCH v3 1/5] mm: Make per-VMA locks available universally
Suren Baghdasaryan <[email protected]> Mon, 3 Aug 2026 08:24:44 -0700
| Newsgroups | org.kvack.linux-mm,org.kernel.vger.linux-kernel,org.kernel.vger.netdev |
|---|---|
| Message-ID | <CAJuCfpGezxdaSme_QpHVq-QVeZAUaF360_Ajvkrn3QqDcSQVog@mail.gmail.com> |
On Sun, Aug 2, 2026 at 2:55=E2=80=AFPM Suren Baghdasaryan <[email protected]= m> wrote: > > From: Dave Hansen <[email protected]> > > The per-VMA locks have been around for several years. They've had some > bugs worked out of them and have seen quite wide use. However, they > are still only available when architectures explicitly enable them. > Remove the conditional compilation around the per-VMA locks, making > them available on all architectures and configs. > > The approach up to now seemed to be to add ARCH_SUPPORTS_PER_VMA_LOCK > when the architecture started using per-VMA locks in the fault > handler. But, contrary to the naming, the Kconfig option does not > really indicate whether the architecture supports per-VMA locks or > not. It is more of a marker for whether the architecture is likely to > benefit from per-VMA locks. > > To me, the most important thing side-effect of universal availability > is letting per-VMA locks be used in SMP=3Dn configs. This lets us use > per-VMA locking in all x86 code without fallbacks. > > Overall, this just generally makes the kernel simpler. Just look at > the diffstat. It also opens the door to users that want to use the > per-VMA locks in common code. Doing *that* brings additional > simplifications. > > The downside of this is adding some fields to vm_area_struct and > mm_struct. There are likely ways to optimize this, especially for > things like SMP=3Dn configs. For now, do the simplest thing: use the > same implementation everywhere. > > Signed-off-by: Dave Hansen <[email protected]> > Signed-off-by: Suren Baghdasaryan <[email protected]> > Cc: Suren Baghdasaryan <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: "Liam R. Howlett" <[email protected]> > Cc: Lorenzo Stoakes <[email protected]> > Cc: Vlastimil Babka <[email protected]> > Cc: Shakeel Butt <[email protected]> > Cc: [email protected] > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Arve Hj=C3=B8nnev=C3=A5g <[email protected]> > Cc: Todd Kjos <[email protected]> > Cc: Christian Brauner <[email protected]> > Cc: Carlos Llamas <[email protected]> > Cc: Alice Ryhl <[email protected]> > Cc: "David S. Miller" <[email protected]> > Cc: David Ahern <[email protected]> > Cc: [email protected] > --- > arch/arm/Kconfig | 1 - > arch/arm64/Kconfig | 1 - > arch/loongarch/Kconfig | 1 - > arch/powerpc/platforms/powernv/Kconfig | 1 - > arch/powerpc/platforms/pseries/Kconfig | 1 - > arch/riscv/Kconfig | 1 - > arch/s390/Kconfig | 1 - > arch/x86/Kconfig | 2 - > fs/proc/internal.h | 2 - > fs/proc/task_mmu.c | 93 -------------------------- > include/linux/mm.h | 12 ---- > include/linux/mm_types.h | 8 +-- > include/linux/mmap_lock.h | 50 -------------- > kernel/bpf/stackmap.c | 16 +---- > kernel/bpf/task_iter.c | 5 -- > kernel/fork.c | 2 - > mm/Kconfig | 13 ---- > mm/Kconfig.debug | 1 - > mm/debug.c | 4 -- > mm/init-mm.c | 2 - > mm/memory.c | 2 - > mm/mmap_lock.c | 24 ------- > mm/pagewalk.c | 2 - > mm/rmap.c | 2 - > mm/userfaultfd.c | 55 --------------- > rust/kernel/mm.rs | 22 +++--- > tools/testing/vma/include/dup.h | 5 +- > tools/testing/vma/vma_internal.h | 1 - > 28 files changed, 13 insertions(+), 317 deletions(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 9187240a02db..f815209167cd 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -41,7 +41,6 @@ config ARM > select ARCH_SUPPORTS_ATOMIC_RMW > select ARCH_SUPPORTS_CFI > select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE > - select ARCH_SUPPORTS_PER_VMA_LOCK > select ARCH_SUPPORTS_RT > select ARCH_USE_BUILTIN_BSWAP > select ARCH_USE_CMPXCHG_LOCKREF > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 11a9c534b7b4..21eb64b24a2c 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -81,7 +81,6 @@ config ARM64 > select ARCH_HAS_PTE_PROTNONE > select ARCH_SUPPORTS_NUMA_BALANCING > select ARCH_SUPPORTS_PAGE_TABLE_CHECK > - select ARCH_SUPPORTS_PER_VMA_LOCK > select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE > select ARCH_SUPPORTS_RT > select ARCH_SUPPORTS_SCHED_SMT > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > index e20acbe5fe7b..7741e39eca2b 100644 > --- a/arch/loongarch/Kconfig > +++ b/arch/loongarch/Kconfig > @@ -69,7 +69,6 @@ config LOONGARCH > select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS > select ARCH_HAS_PTE_PROTNONE if 64BIT > select ARCH_SUPPORTS_NUMA_BALANCING if NUMA > - select ARCH_SUPPORTS_PER_VMA_LOCK > select ARCH_SUPPORTS_RT > select ARCH_SUPPORTS_SCHED_SMT if SMP > select ARCH_SUPPORTS_SCHED_MC if SMP > diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platfo= rms/powernv/Kconfig > index b5ad7c173ef0..dd8f6060fb7a 100644 > --- a/arch/powerpc/platforms/powernv/Kconfig > +++ b/arch/powerpc/platforms/powernv/Kconfig > @@ -17,7 +17,6 @@ config PPC_POWERNV > select PPC_DOORBELL > select MMU_NOTIFIER > select FORCE_SMP > - select ARCH_SUPPORTS_PER_VMA_LOCK > select PPC_RADIX_BROADCAST_TLBIE if PPC_RADIX_MMU > default y > > diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platfo= rms/pseries/Kconfig > index 74910ce3a541..7d125e288f6e 100644 > --- a/arch/powerpc/platforms/pseries/Kconfig > +++ b/arch/powerpc/platforms/pseries/Kconfig > @@ -23,7 +23,6 @@ config PPC_PSERIES > select HOTPLUG_CPU > select FORCE_SMP > select SWIOTLB > - select ARCH_SUPPORTS_PER_VMA_LOCK > select PPC_RADIX_BROADCAST_TLBIE if PPC_RADIX_MMU > default y > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 7b9c373d82fa..faa85a031fe5 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -70,7 +70,6 @@ config RISCV > select ARCH_SUPPORTS_LTO_CLANG_THIN > select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS if 64BIT && MMU > select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU > - select ARCH_SUPPORTS_PER_VMA_LOCK if MMU > select ARCH_HAS_PTE_PROTNONE if MMU > select ARCH_SUPPORTS_RT > select ARCH_SUPPORTS_SHADOW_CALL_STACK if HAVE_SHADOW_CALL_STACK > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index ab8fccc2cc4e..d1274bca8c39 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -151,7 +151,6 @@ config S390 > select ARCH_HAS_PTE_PROTNONE > select ARCH_SUPPORTS_NUMA_BALANCING > select ARCH_SUPPORTS_PAGE_TABLE_CHECK > - select ARCH_SUPPORTS_PER_VMA_LOCK > select ARCH_USE_BUILTIN_BSWAP > select ARCH_USE_CMPXCHG_LOCKREF > select ARCH_USE_SYM_ANNOTATIONS > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index fb298e219179..79479d29576f 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -27,7 +27,6 @@ config X86_64 > select ARCH_HAS_GIGANTIC_PAGE > select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS > select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 > - select ARCH_SUPPORTS_PER_VMA_LOCK > select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE > select HAVE_ARCH_SOFT_DIRTY > select MODULES_USE_ELF_RELA > @@ -1846,7 +1845,6 @@ config X86_USER_SHADOW_STACK > bool "X86 userspace shadow stack" > depends on AS_WRUSS > depends on X86_64 > - depends on PER_VMA_LOCK > select ARCH_USES_HIGH_VMA_FLAGS > select ARCH_HAS_USER_SHADOW_STACK > select X86_CET > diff --git a/fs/proc/internal.h b/fs/proc/internal.h > index b232e1098117..6713757da099 100644 > --- a/fs/proc/internal.h > +++ b/fs/proc/internal.h > @@ -385,10 +385,8 @@ struct mem_size_stats; > > struct proc_maps_locking_ctx { > struct mm_struct *mm; > -#ifdef CONFIG_PER_VMA_LOCK > bool mmap_locked; > struct vm_area_struct *locked_vma; > -#endif > }; > > struct proc_maps_private { > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 817e3e0f9194..096bf0b0b9e0 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -130,8 +130,6 @@ static void release_task_mempolicy(struct proc_maps_p= rivate *priv) > } > #endif > > -#ifdef CONFIG_PER_VMA_LOCK > - > static inline int lock_ctx_mm(struct proc_maps_locking_ctx *lock_ctx) > { > int ret =3D mmap_read_lock_killable(lock_ctx->mm); > @@ -233,46 +231,6 @@ static inline void reacquire_rcu(struct proc_maps_pr= ivate *priv) > vma_iter_set(&priv->iter, priv->lock_ctx.locked_vma->vm_end); > } > > -#else /* CONFIG_PER_VMA_LOCK */ > - > -static inline int lock_ctx_mm(struct proc_maps_locking_ctx *lock_ctx) > -{ > - return mmap_read_lock_killable(lock_ctx->mm); > -} > - > -static inline void unlock_ctx_mm(struct proc_maps_locking_ctx *lock_ctx) > -{ > - mmap_read_unlock(lock_ctx->mm); > -} > - > -static inline bool lock_vma_range(struct seq_file *m, > - struct proc_maps_locking_ctx *lock_ctx) > -{ > - return lock_ctx_mm(lock_ctx) =3D=3D 0; > -} > - > -static inline void unlock_vma_range(struct proc_maps_locking_ctx *lock_c= tx) > -{ > - unlock_ctx_mm(lock_ctx); > -} > - > -static struct vm_area_struct *get_next_vma(struct proc_maps_private *pri= v, > - loff_t last_pos) > -{ > - return vma_next(&priv->iter); > -} > - > -static inline bool fallback_to_mmap_lock(struct proc_maps_private *priv, > - loff_t pos) > -{ > - return false; > -} > - > -static inline void drop_rcu(struct proc_maps_private *priv) {} > -static inline void reacquire_rcu(struct proc_maps_private *priv) {} > - > -#endif /* CONFIG_PER_VMA_LOCK */ > - > static struct vm_area_struct *proc_get_vma(struct seq_file *m, loff_t *p= pos) > { > struct proc_maps_private *priv =3D m->private; > @@ -560,8 +518,6 @@ static int pid_maps_open(struct inode *inode, struct = file *file) > PROCMAP_QUERY_VMA_FLAGS \ > ) > > -#ifdef CONFIG_PER_VMA_LOCK > - > static int query_vma_setup(struct proc_maps_locking_ctx *lock_ctx) > { > reset_lock_ctx(lock_ctx); > @@ -612,26 +568,6 @@ static struct vm_area_struct *query_vma_find_by_addr= (struct proc_maps_locking_ct > return vma; > } > > -#else /* CONFIG_PER_VMA_LOCK */ > - > -static int query_vma_setup(struct proc_maps_locking_ctx *lock_ctx) > -{ > - return mmap_read_lock_killable(lock_ctx->mm); > -} > - > -static void query_vma_teardown(struct proc_maps_locking_ctx *lock_ctx) > -{ > - mmap_read_unlock(lock_ctx->mm); > -} > - > -static struct vm_area_struct *query_vma_find_by_addr(struct proc_maps_lo= cking_ctx *lock_ctx, > - unsigned long addr) > -{ > - return find_vma(lock_ctx->mm, addr); > -} > - > -#endif /* CONFIG_PER_VMA_LOCK */ > - > static struct vm_area_struct *query_matching_vma(struct proc_maps_lockin= g_ctx *lock_ctx, > unsigned long addr, u32 = flags) > { > @@ -1314,8 +1250,6 @@ static const struct mm_walk_ops smaps_shmem_walk_op= s =3D { > .walk_lock =3D PGWALK_RDLOCK, > }; > > -#ifdef CONFIG_PER_VMA_LOCK > - > static const struct mm_walk_ops smaps_walk_vma_lock_ops =3D { > .pmd_entry =3D smaps_pte_range, > .hugetlb_entry =3D smaps_hugetlb_range, > @@ -1345,22 +1279,6 @@ get_smaps_shmem_walk_ops(struct proc_maps_private = *priv) > return &smaps_shmem_walk_vma_lock_ops; > } > > -#else /* CONFIG_PER_VMA_LOCK */ > - > -static inline const struct mm_walk_ops * > -get_smaps_walk_ops(struct proc_maps_private *priv) > -{ > - return &smaps_walk_ops; > -} > - > -static inline const struct mm_walk_ops * > -get_smaps_shmem_walk_ops(struct proc_maps_private *priv) > -{ > - return &smaps_shmem_walk_ops; > -} > - > -#endif /* CONFIG_PER_VMA_LOCK */ > - > /* > * Gather mem stats from @vma with the indicated beginning > * address @start, and keep them in @mss. > @@ -3497,7 +3415,6 @@ static const struct mm_walk_ops show_numa_ops =3D { > .walk_lock =3D PGWALK_RDLOCK, > }; > > -#ifdef CONFIG_PER_VMA_LOCK > static const struct mm_walk_ops show_numa_vma_lock_ops =3D { > .hugetlb_entry =3D gather_hugetlb_stats, > .pmd_entry =3D gather_pte_stats, > @@ -3512,16 +3429,6 @@ get_show_numa_ops(struct proc_maps_private *priv) > return &show_numa_vma_lock_ops; > } > > -#else /* CONFIG_PER_VMA_LOCK */ > - > -static inline const struct mm_walk_ops * > -get_show_numa_ops(struct proc_maps_private *priv) > -{ > - return &show_numa_ops; > -} > - > -#endif /* CONFIG_PER_VMA_LOCK */ > - > /* > * Display pages allocated per node and memory policy via /proc. > */ > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 7fabe6c66b4b..d9850f846242 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -931,7 +931,6 @@ static inline void vma_numab_state_free(struct vm_are= a_struct *vma) {} > * These must be here rather than mmap_lock.h as dependent on vm_fault t= ype, > * declared in this header. > */ > -#ifdef CONFIG_PER_VMA_LOCK > static inline void release_fault_lock(struct vm_fault *vmf) > { > if (vmf->flags & FAULT_FLAG_VMA_LOCK) > @@ -947,17 +946,6 @@ static inline void assert_fault_locked(const struct = vm_fault *vmf) > else > mmap_assert_locked(vmf->vma->vm_mm); > } > -#else > -static inline void release_fault_lock(struct vm_fault *vmf) > -{ > - mmap_read_unlock(vmf->vma->vm_mm); > -} > - > -static inline void assert_fault_locked(const struct vm_fault *vmf) > -{ > - mmap_assert_locked(vmf->vma->vm_mm); > -} > -#endif /* CONFIG_PER_VMA_LOCK */ > > static inline bool mm_flags_test(int flag, const struct mm_struct *mm) > { > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index b5d4cd3b067b..d8e246fd09d3 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -950,7 +950,6 @@ struct vm_area_struct { > vma_flags_t flags; > }; > > -#ifdef CONFIG_PER_VMA_LOCK > /* > * Can only be written (using WRITE_ONCE()) while holding both: > * - mmap_lock (in write mode) > @@ -966,7 +965,7 @@ struct vm_area_struct { > * slowpath. > */ > unsigned int vm_lock_seq; > -#endif > + > /* > * Low 32-bits of virtual page offset. > * See vma_start_virt_pgoff() comment for details. > @@ -1003,7 +1002,6 @@ struct vm_area_struct { > #ifdef CONFIG_NUMA_BALANCING > struct vma_numab_state *numab_state; /* NUMA Balancing state *= / > #endif > -#ifdef CONFIG_PER_VMA_LOCK > /* > * Used to keep track of firstly, whether the VMA is attached, se= condly, > * if attached, how many read locks are taken, and thirdly, if th= e > @@ -1046,7 +1044,6 @@ struct vm_area_struct { > #ifdef CONFIG_DEBUG_LOCK_ALLOC > struct lockdep_map vmlock_dep_map; > #endif > -#endif > #ifdef CONFIG_64BIT > /* > * High 32-bits of virtual page offset. > @@ -1254,7 +1251,6 @@ struct mm_struct { > * init_mm.mmlist, and are prote= cted > * by mmlist_lock > */ > -#ifdef CONFIG_PER_VMA_LOCK > struct rcuwait vma_writer_wait; > /* > * This field has lock-like semantics, meaning it is some= times > @@ -1274,7 +1270,7 @@ struct mm_struct { > * mmap_lock. > */ > seqcount_t mm_lock_seq; > -#endif > + > struct futex_mm_data futex; > > unsigned long hiwater_rss; /* High-watermark of RSS usage= */ > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h > index 87f77e3da77f..eb32b482434e 100644 > --- a/include/linux/mmap_lock.h > +++ b/include/linux/mmap_lock.h > @@ -76,8 +76,6 @@ static inline void mmap_assert_write_locked(const struc= t mm_struct *mm) > rwsem_assert_held_write(&mm->mmap_lock); > } > > -#ifdef CONFIG_PER_VMA_LOCK > - > #ifdef CONFIG_LOCKDEP > #define __vma_lockdep_map(vma) (&vma->vmlock_dep_map) > #else > @@ -484,54 +482,6 @@ struct vm_area_struct *lock_next_vma(struct mm_struc= t *mm, > struct vma_iterator *iter, > unsigned long address); > > -#else /* CONFIG_PER_VMA_LOCK */ > - > -static inline void mm_lock_seqcount_init(struct mm_struct *mm) {} > -static inline void mm_lock_seqcount_begin(struct mm_struct *mm) {} > -static inline void mm_lock_seqcount_end(struct mm_struct *mm) {} > - > -static inline bool mmap_lock_speculate_try_begin(struct mm_struct *mm, u= nsigned int *seq) > -{ > - return false; > -} > - > -static inline bool mmap_lock_speculate_retry(struct mm_struct *mm, unsig= ned int seq) > -{ > - return true; > -} > -static inline void vma_lock_init(struct vm_area_struct *vma, bool reset_= refcnt) {} > -static inline void vma_end_read(struct vm_area_struct *vma) {} > -static inline void vma_start_write(struct vm_area_struct *vma) {} > -static inline __must_check > -int vma_start_write_killable(struct vm_area_struct *vma) { return 0; } > -static inline void vma_assert_write_locked(struct vm_area_struct *vma) > - { mmap_assert_write_locked(vma->vm_mm); } > -static inline bool vma_is_attached(struct vm_area_struct *vma) > - { return true; } > -static inline void vma_assert_attached(struct vm_area_struct *vma) {} > -static inline void vma_assert_detached(struct vm_area_struct *vma) {} > -static inline void vma_mark_attached(struct vm_area_struct *vma) {} > -static inline void vma_mark_detached(struct vm_area_struct *vma) {} > - > -static inline struct vm_area_struct *lock_vma_under_rcu(struct mm_struct= *mm, > - unsigned long address) > -{ > - return NULL; > -} > - > -static inline void vma_assert_locked(struct vm_area_struct *vma) > -{ > - mmap_assert_locked(vma->vm_mm); > -} > - > -static inline void vma_assert_stabilised(struct vm_area_struct *vma) > -{ > - /* If no VMA locks, then either mmap lock suffices to stabilise. = */ > - mmap_assert_locked(vma->vm_mm); > -} > - > -#endif /* CONFIG_PER_VMA_LOCK */ Now that I'm looking closer into this, I think we would break NOMMU case because nommu.c does not take VMA write locks at all. So, lock_vma_under_rcu() for example would always succeed. Extra per_VMA lock-related fields in the vm_area_struct and mm_struct would also inflate NOMMU structure sizes without them being used. I'm not sure if this is an issue we should consider. > - > static inline void vma_assert_can_modify(struct vm_area_struct *vma) > { > if (vma_is_attached(vma)) > diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c > index 41fe87d7302f..8848e26ef581 100644 > --- a/kernel/bpf/stackmap.c > +++ b/kernel/bpf/stackmap.c > @@ -272,13 +272,8 @@ struct stack_map_vma_lock { > /* > * Acquire a stable read-side reference on the VMA covering @ip. > * > - * With CONFIG_PER_VMA_LOCK=3Dy this returns a VMA with its per-VMA read > - * lock held and mmap_lock dropped, so the caller may sleep. > - * > - * With CONFIG_PER_VMA_LOCK=3Dn it returns a VMA with mmap_lock still > - * held; the caller must snapshot any fields it needs and pin vm_file > - * with get_file() before stack_map_unlock_vma() drops mmap_lock, as > - * the VMA may be split, merged, or freed after that. > + * This returns a VMA with its per-VMA read lock held and mmap_lock > + * dropped, so the caller may sleep. > * > * Returns NULL on failure, in which case no lock is held. > */ > @@ -288,7 +283,6 @@ stack_map_lock_vma(struct stack_map_vma_lock *lock, u= nsigned long ip) > struct mm_struct *mm =3D lock->mm; > struct vm_area_struct *vma; > > - /* noop under !CONFIG_PER_VMA_LOCK */ > vma =3D lock_vma_under_rcu(mm, ip); > if (vma) { > lock->vma =3D vma; > @@ -308,13 +302,11 @@ stack_map_lock_vma(struct stack_map_vma_lock *lock,= unsigned long ip) > return NULL; > } > > -#ifdef CONFIG_PER_VMA_LOCK > if (!vma_start_read_locked(vma)) { > mmap_read_unlock(mm); > return NULL; > } > mmap_read_unlock(mm); > -#endif > > lock->vma =3D vma; > return vma; > @@ -322,11 +314,7 @@ stack_map_lock_vma(struct stack_map_vma_lock *lock, = unsigned long ip) > > static void stack_map_unlock_vma(struct stack_map_vma_lock *lock) > { > -#ifdef CONFIG_PER_VMA_LOCK > vma_end_read(lock->vma); > -#else > - mmap_read_unlock(lock->mm); > -#endif > lock->vma =3D NULL; > } > > diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c > index e791ae065c39..6cf815bc84be 100644 > --- a/kernel/bpf/task_iter.c > +++ b/kernel/bpf/task_iter.c > @@ -835,11 +835,6 @@ __bpf_kfunc int bpf_iter_task_vma_new(struct bpf_ite= r_task_vma *it, > BUILD_BUG_ON(sizeof(struct bpf_iter_task_vma_kern) !=3D sizeof(st= ruct bpf_iter_task_vma)); > BUILD_BUG_ON(__alignof__(struct bpf_iter_task_vma_kern) !=3D __al= ignof__(struct bpf_iter_task_vma)); > > - if (!IS_ENABLED(CONFIG_PER_VMA_LOCK)) { > - kit->data =3D NULL; > - return -EOPNOTSUPP; > - } > - > /* > * Reject irqs-disabled contexts including NMI. Operations used > * by _next() and _destroy() (vma_end_read, fput, bpf_iter_mmput_= async) > diff --git a/kernel/fork.c b/kernel/fork.c > index f0e2e131a9a5..ff91f5f66c80 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1077,9 +1077,7 @@ static void mmap_init_lock(struct mm_struct *mm) > { > init_rwsem(&mm->mmap_lock); > mm_lock_seqcount_init(mm); > -#ifdef CONFIG_PER_VMA_LOCK > rcuwait_init(&mm->vma_writer_wait); > -#endif > } > > static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struc= t *p) > diff --git a/mm/Kconfig b/mm/Kconfig > index 060190e12bce..77103b46b679 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -1425,19 +1425,6 @@ config LRU_GEN_STATS > config LRU_GEN_WALKS_MMU > def_bool y > depends on LRU_GEN && ARCH_HAS_HW_PTE_YOUNG > -# } > - > -config ARCH_SUPPORTS_PER_VMA_LOCK > - def_bool n > - > -config PER_VMA_LOCK > - def_bool y > - depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP > - help > - Allow per-vma locking during page fault handling. > - > - This feature allows locking each virtual memory area separately= when > - handling page faults instead of taking mmap_lock. > > config LOCK_MM_AND_FIND_VMA > bool > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug > index 5737a504efbb..1dd150edfe71 100644 > --- a/mm/Kconfig.debug > +++ b/mm/Kconfig.debug > @@ -310,7 +310,6 @@ config DEBUG_KMEMLEAK_VERBOSE > > config PER_VMA_LOCK_STATS > bool "Statistics for per-vma locks" > - depends on PER_VMA_LOCK > help > Say Y here to enable success, retry and failure counters of pag= e > faults handled under protection of per-vma locks. When enabled,= the > diff --git a/mm/debug.c b/mm/debug.c > index 9a0297b3988d..655e6bcc0e8d 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -157,17 +157,13 @@ void dump_vma(const struct vm_area_struct *vma) > pr_emerg("vma %px start %px end %px mm %px\n" > "prot %lx anon_vma %px vm_ops %px\n" > "pgoff %lx file %px private_data %px\n" > -#ifdef CONFIG_PER_VMA_LOCK > "refcnt %x\n" > -#endif > "flags: %#lx(%pGv)\n", > vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_= mm, > (unsigned long)pgprot_val(vma->vm_page_prot), > vma->anon_vma, vma->vm_ops, vma_start_pgoff(vma), > vma->vm_file, vma->vm_private_data, > -#ifdef CONFIG_PER_VMA_LOCK > refcount_read(&vma->vm_refcnt), > -#endif > vma->vm_flags, &vma->vm_flags); > } > EXPORT_SYMBOL(dump_vma); > diff --git a/mm/init-mm.c b/mm/init-mm.c > index 3e792aad7626..a1bb2c2d0284 100644 > --- a/mm/init-mm.c > +++ b/mm/init-mm.c > @@ -39,10 +39,8 @@ struct mm_struct init_mm =3D { > .page_table_lock =3D __SPIN_LOCK_UNLOCKED(init_mm.page_table_loc= k), > .arg_lock =3D __SPIN_LOCK_UNLOCKED(init_mm.arg_lock), > .mmlist =3D LIST_HEAD_INIT(init_mm.mmlist), > -#ifdef CONFIG_PER_VMA_LOCK > .vma_writer_wait =3D __RCUWAIT_INITIALIZER(init_mm.vma_writer_wai= t), > .mm_lock_seq =3D SEQCNT_ZERO(init_mm.mm_lock_seq), > -#endif > #ifdef CONFIG_SCHED_MM_CID > .mm_cid.lock =3D __RAW_SPIN_LOCK_UNLOCKED(init_mm.mm_cid.lock), > #endif > diff --git a/mm/memory.c b/mm/memory.c > index a620d425ec95..f109f6c87b28 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -6813,7 +6813,6 @@ static vm_fault_t sanitize_fault_flags(struct vm_ar= ea_struct *vma, > !is_cow_mapping(vma->vm_flags))) > return VM_FAULT_SIGSEGV; > } > -#ifdef CONFIG_PER_VMA_LOCK > /* > * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT becau= se of > * the assumption that lock is dropped on VM_FAULT_RETRY. > @@ -6822,7 +6821,6 @@ static vm_fault_t sanitize_fault_flags(struct vm_ar= ea_struct *vma, > (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) = =3D=3D > (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT))) > return VM_FAULT_SIGSEGV; > -#endif > > return 0; > } > diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c > index 898c2ef1e958..e20d01e8d38f 100644 > --- a/mm/mmap_lock.c > +++ b/mm/mmap_lock.c > @@ -43,9 +43,6 @@ void __mmap_lock_do_trace_released(struct mm_struct *mm= , bool write) > EXPORT_SYMBOL(__mmap_lock_do_trace_released); > #endif /* CONFIG_TRACING */ > > -#ifdef CONFIG_MMU > -#ifdef CONFIG_PER_VMA_LOCK > - > /* State shared across __vma_[start, end]_exclude_readers. */ > struct vma_exclude_readers_state { > /* Input parameters. */ > @@ -431,7 +428,6 @@ struct vm_area_struct *lock_next_vma(struct mm_struct= *mm, > > return vma; > } > -#endif /* CONFIG_PER_VMA_LOCK */ > > #ifdef CONFIG_LOCK_MM_AND_FIND_VMA > #include <linux/extable.h> > @@ -548,23 +544,3 @@ struct vm_area_struct *lock_mm_and_find_vma(struct m= m_struct *mm, > return NULL; > } > #endif /* CONFIG_LOCK_MM_AND_FIND_VMA */ > - > -#else /* CONFIG_MMU */ > - > -/* > - * At least xtensa ends up having protection faults even with no > - * MMU.. No stack expansion, at least. > - */ > -struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, > - unsigned long addr, struct pt_regs *regs) > -{ > - struct vm_area_struct *vma; > - > - mmap_read_lock(mm); > - vma =3D vma_lookup(mm, addr); > - if (!vma) > - mmap_read_unlock(mm); > - return vma; > -} > - > -#endif /* CONFIG_MMU */ > diff --git a/mm/pagewalk.c b/mm/pagewalk.c > index ed4860c01936..fbcf64c59a97 100644 > --- a/mm/pagewalk.c > +++ b/mm/pagewalk.c > @@ -446,7 +446,6 @@ static inline void process_mm_walk_lock(struct mm_str= uct *mm, > static inline void process_vma_walk_lock(struct vm_area_struct *vma, > enum page_walk_lock walk_lock) > { > -#ifdef CONFIG_PER_VMA_LOCK > switch (walk_lock) { > case PGWALK_WRLOCK: > vma_start_write(vma); > @@ -461,7 +460,6 @@ static inline void process_vma_walk_lock(struct vm_ar= ea_struct *vma, > /* PGWALK_RDLOCK is handled by process_mm_walk_lock */ > break; > } > -#endif > } > > /* > diff --git a/mm/rmap.c b/mm/rmap.c > index b917431759ee..4e4a4b747977 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -260,11 +260,9 @@ static void check_anon_vma_clone(struct vm_area_stru= ct *dst, > /* For the anon_vma to be compatible, it can only be singular. */ > VM_WARN_ON_ONCE(operation =3D=3D VMA_OP_MERGE_UNFAULTED && > !list_is_singular(&src->anon_vma_chain)); > -#ifdef CONFIG_PER_VMA_LOCK > /* Only merging an unfaulted VMA leaves the destination attached.= */ > VM_WARN_ON_ONCE(operation !=3D VMA_OP_MERGE_UNFAULTED && > vma_is_attached(dst)); > -#endif > } > > static void maybe_reuse_anon_vma(struct vm_area_struct *dst, > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index 258b03182a78..edd90892f8cc 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -122,7 +122,6 @@ struct vm_area_struct *find_vma_and_prepare_anon(stru= ct mm_struct *mm, > return vma; > } > > -#ifdef CONFIG_PER_VMA_LOCK > /* > * uffd_lock_vma() - Lookup and lock vma corresponding to @address. > * @mm: mm to search vma in. > @@ -182,34 +181,6 @@ static void uffd_mfill_unlock(struct vm_area_struct = *vma) > vma_end_read(vma); > } > > -#else > - > -static struct vm_area_struct *uffd_mfill_lock(struct mm_struct *dst_mm, > - unsigned long dst_start, > - unsigned long len) > -{ > - struct vm_area_struct *dst_vma; > - > - mmap_read_lock(dst_mm); > - dst_vma =3D find_vma_and_prepare_anon(dst_mm, dst_start); > - if (IS_ERR(dst_vma)) > - goto out_unlock; > - > - if (validate_dst_vma(dst_vma, dst_start + len)) > - return dst_vma; > - > - dst_vma =3D ERR_PTR(-ENOENT); > -out_unlock: > - mmap_read_unlock(dst_mm); > - return dst_vma; > -} > - > -static void uffd_mfill_unlock(struct vm_area_struct *vma) > -{ > - mmap_read_unlock(vma->vm_mm); > -} > -#endif > - > static void mfill_put_vma(struct mfill_state *state) > { > if (!state->vma) > @@ -1852,7 +1823,6 @@ int find_vmas_mm_locked(struct mm_struct *mm, > return 0; > } > > -#ifdef CONFIG_PER_VMA_LOCK > static int uffd_move_lock(struct mm_struct *mm, > unsigned long dst_start, > unsigned long src_start, > @@ -1927,31 +1897,6 @@ static void uffd_move_unlock(struct vm_area_struct= *dst_vma, > vma_end_read(dst_vma); > } > > -#else > - > -static int uffd_move_lock(struct mm_struct *mm, > - unsigned long dst_start, > - unsigned long src_start, > - struct vm_area_struct **dst_vmap, > - struct vm_area_struct **src_vmap) > -{ > - int err; > - > - mmap_read_lock(mm); > - err =3D find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, s= rc_vmap); > - if (err) > - mmap_read_unlock(mm); > - return err; > -} > - > -static void uffd_move_unlock(struct vm_area_struct *dst_vma, > - struct vm_area_struct *src_vma) > -{ > - mmap_assert_locked(src_vma->vm_mm); > - mmap_read_unlock(dst_vma->vm_mm); > -} > -#endif > - > /** > * move_pages - move arbitrary anonymous pages of an existing vma > * @ctx: pointer to the userfaultfd context > diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs > index 4764d7b68f2a..2633e704c83d 100644 > --- a/rust/kernel/mm.rs > +++ b/rust/kernel/mm.rs > @@ -174,26 +174,20 @@ pub unsafe fn from_raw<'a>(ptr: *const bindings::mm= _struct) -> &'a MmWithUser { > /// When per-vma locks are disabled, this always returns `None`. > #[inline] > pub fn lock_vma_under_rcu(&self, vma_addr: usize) -> Option<VmaReadG= uard<'_>> { > - #[cfg(CONFIG_PER_VMA_LOCK)] > { > // SAFETY: Calling `bindings::lock_vma_under_rcu` is always = okay given an mm where > // `mm_users` is non-zero. > let vma =3D unsafe { bindings::lock_vma_under_rcu(self.as_ra= w(), vma_addr) }; > - if !vma.is_null() { > - return Some(VmaReadGuard { > - // SAFETY: If `lock_vma_under_rcu` returns a non-nul= l ptr, then it points at a > - // valid vma. The vma is stable for as long as the v= ma read lock is held. > - vma: unsafe { VmaRef::from_raw(vma) }, > - _nts: NotThreadSafe, > - }); > + if vma.is_null() { > + return None; > } > + Some(VmaReadGuard { > + // SAFETY: If `lock_vma_under_rcu` returns a non-null pt= r, then it points at a > + // valid vma. The vma is stable for as long as the vma r= ead lock is held. > + vma: unsafe { VmaRef::from_raw(vma) }, > + _nts: NotThreadSafe, > + }) > } > - > - // Silence warnings about unused variables. > - #[cfg(not(CONFIG_PER_VMA_LOCK))] > - let _ =3D vma_addr; > - > - None > } > > /// Lock the mmap read lock. > diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/= dup.h > index 800e5fa02d78..362feda28526 100644 > --- a/tools/testing/vma/include/dup.h > +++ b/tools/testing/vma/include/dup.h > @@ -582,7 +582,6 @@ struct vm_area_struct { > vma_flags_t flags; > }; > > -#ifdef CONFIG_PER_VMA_LOCK > /* > * Can only be written (using WRITE_ONCE()) while holding both: > * - mmap_lock (in write mode) > @@ -598,7 +597,7 @@ struct vm_area_struct { > * slowpath. > */ > unsigned int vm_lock_seq; > -#endif > + > unsigned int __vm_virt_pgoff_lo; > > /* > @@ -632,10 +631,8 @@ struct vm_area_struct { > #ifdef CONFIG_NUMA_BALANCING > struct vma_numab_state *numab_state; /* NUMA Balancing state *= / > #endif > -#ifdef CONFIG_PER_VMA_LOCK > /* Unstable RCU readers are allowed to read this. */ > refcount_t vm_refcnt; > -#endif > #ifdef CONFIG_64BIT > unsigned int __vm_virt_pgoff_hi; > #endif > diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_int= ernal.h > index 8a48b231aa7a..54d5c3360aa2 100644 > --- a/tools/testing/vma/vma_internal.h > +++ b/tools/testing/vma/vma_internal.h > @@ -15,7 +15,6 @@ > #include <stdlib.h> > > #define CONFIG_MMU 1 > -#define CONFIG_PER_VMA_LOCK 1 > > #ifdef __CONCAT > #undef __CONCAT > -- > 2.55.0.508.g3f0d502094-goog >