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Message-ID: <c188d550-7d49-4df5-8908-4ebdc016db03@lucifer.local>
Date: Mon, 28 Apr 2025 21:28:13 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
Pedro Falcato <pfalcato@...e.de>, David Hildenbrand <david@...hat.com>,
Kees Cook <kees@...nel.org>, Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
Suren Baghdasaryan <surenb@...gle.com>, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/4] mm: perform VMA allocation, freeing, duplication
in mm
On Mon, Apr 28, 2025 at 03:14:46PM -0400, Liam R. Howlett wrote:
> * Lorenzo Stoakes <lorenzo.stoakes@...cle.com> [250428 11:28]:
> > Right now these are performed in kernel/fork.c which is odd and a violation
> > of separation of concerns, as well as preventing us from integrating this
> > and related logic into userland VMA testing going forward, and perhaps more
> > importantly - enabling us to, in a subsequent commit, make VMA
> > allocation/freeing a purely internal mm operation.
> >
> > There is a fly in the ointment - nommu - mmap.c is not compiled if
> > CONFIG_MMU not set, and neither is vma.c.
> >
> > To square the circle, let's add a new file - vma_init.c. This will be
> > compiled for both CONFIG_MMU and nommu builds, and will also form part of
> > the VMA userland testing.
> >
> > This allows us to de-duplicate code, while maintaining separation of
> > concerns and the ability for us to userland test this logic.
> >
> > Update the VMA userland tests accordingly, additionally adding a
> > detach_free_vma() helper function to correctly detach VMAs before freeing
> > them in test code, as this change was triggering the assert for this.
> >
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
>
> One small nit below.
>
> Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>
Thanks!
I see Andrew already fixed up the nit :)
>
> > ---
> > MAINTAINERS | 1 +
> > kernel/fork.c | 88 -------------------
> > mm/Makefile | 2 +-
> > mm/mmap.c | 3 +-
> > mm/nommu.c | 4 +-
> > mm/vma.h | 7 ++
> > mm/vma_init.c | 101 ++++++++++++++++++++++
> > tools/testing/vma/Makefile | 2 +-
> > tools/testing/vma/vma.c | 26 ++++--
> > tools/testing/vma/vma_internal.h | 143 +++++++++++++++++++++++++------
> > 10 files changed, 251 insertions(+), 126 deletions(-)
> > create mode 100644 mm/vma_init.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 1ee1c22e6e36..d274e6802ba5 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -15656,6 +15656,7 @@ F: mm/mseal.c
> > F: mm/vma.c
> > F: mm/vma.h
> > F: mm/vma_exec.c
> > +F: mm/vma_init.c
> > F: mm/vma_internal.h
> > F: tools/testing/selftests/mm/merge.c
> > F: tools/testing/vma/
> > diff --git a/kernel/fork.c b/kernel/fork.c
> > index ac9f9267a473..9e4616dacd82 100644
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -431,88 +431,9 @@ struct kmem_cache *files_cachep;
> > /* SLAB cache for fs_struct structures (tsk->fs) */
> > struct kmem_cache *fs_cachep;
> >
> > -/* SLAB cache for vm_area_struct structures */
> > -static struct kmem_cache *vm_area_cachep;
> > -
> > /* SLAB cache for mm_struct structures (tsk->mm) */
> > static struct kmem_cache *mm_cachep;
> >
> > -struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
> > -{
> > - struct vm_area_struct *vma;
> > -
> > - vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
> > - if (!vma)
> > - return NULL;
> > -
> > - vma_init(vma, mm);
> > -
> > - return vma;
> > -}
> > -
> > -static void vm_area_init_from(const struct vm_area_struct *src,
> > - struct vm_area_struct *dest)
> > -{
> > - dest->vm_mm = src->vm_mm;
> > - dest->vm_ops = src->vm_ops;
> > - dest->vm_start = src->vm_start;
> > - dest->vm_end = src->vm_end;
> > - dest->anon_vma = src->anon_vma;
> > - dest->vm_pgoff = src->vm_pgoff;
> > - dest->vm_file = src->vm_file;
> > - dest->vm_private_data = src->vm_private_data;
> > - vm_flags_init(dest, src->vm_flags);
> > - memcpy(&dest->vm_page_prot, &src->vm_page_prot,
> > - sizeof(dest->vm_page_prot));
> > - /*
> > - * src->shared.rb may be modified concurrently when called from
> > - * dup_mmap(), but the clone will reinitialize it.
> > - */
> > - data_race(memcpy(&dest->shared, &src->shared, sizeof(dest->shared)));
> > - memcpy(&dest->vm_userfaultfd_ctx, &src->vm_userfaultfd_ctx,
> > - sizeof(dest->vm_userfaultfd_ctx));
> > -#ifdef CONFIG_ANON_VMA_NAME
> > - dest->anon_name = src->anon_name;
> > -#endif
> > -#ifdef CONFIG_SWAP
> > - memcpy(&dest->swap_readahead_info, &src->swap_readahead_info,
> > - sizeof(dest->swap_readahead_info));
> > -#endif
> > -#ifndef CONFIG_MMU
> > - dest->vm_region = src->vm_region;
> > -#endif
> > -#ifdef CONFIG_NUMA
> > - dest->vm_policy = src->vm_policy;
> > -#endif
> > -}
> > -
> > -struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
> > -{
> > - struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
> > -
> > - if (!new)
> > - return NULL;
> > -
> > - ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
> > - ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
> > - vm_area_init_from(orig, new);
> > - vma_lock_init(new, true);
> > - INIT_LIST_HEAD(&new->anon_vma_chain);
> > - vma_numab_state_init(new);
> > - dup_anon_vma_name(orig, new);
> > -
> > - return new;
> > -}
> > -
> > -void vm_area_free(struct vm_area_struct *vma)
> > -{
> > - /* The vma should be detached while being destroyed. */
> > - vma_assert_detached(vma);
> > - vma_numab_state_free(vma);
> > - free_anon_vma_name(vma);
> > - kmem_cache_free(vm_area_cachep, vma);
> > -}
> > -
> > static void account_kernel_stack(struct task_struct *tsk, int account)
> > {
> > if (IS_ENABLED(CONFIG_VMAP_STACK)) {
> > @@ -3033,11 +2954,6 @@ void __init mm_cache_init(void)
> >
> > void __init proc_caches_init(void)
> > {
> > - struct kmem_cache_args args = {
> > - .use_freeptr_offset = true,
> > - .freeptr_offset = offsetof(struct vm_area_struct, vm_freeptr),
> > - };
> > -
> > sighand_cachep = kmem_cache_create("sighand_cache",
> > sizeof(struct sighand_struct), 0,
> > SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
> > @@ -3054,10 +2970,6 @@ void __init proc_caches_init(void)
> > sizeof(struct fs_struct), 0,
> > SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
> > NULL);
> > - vm_area_cachep = kmem_cache_create("vm_area_struct",
> > - sizeof(struct vm_area_struct), &args,
> > - SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
> > - SLAB_ACCOUNT);
> > mmap_init();
> > nsproxy_cache_init();
> > }
> > diff --git a/mm/Makefile b/mm/Makefile
> > index 15a901bb431a..690ddcf7d9a1 100644
> > --- a/mm/Makefile
> > +++ b/mm/Makefile
> > @@ -55,7 +55,7 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
> > mm_init.o percpu.o slab_common.o \
> > compaction.o show_mem.o \
> > interval_tree.o list_lru.o workingset.o \
> > - debug.o gup.o mmap_lock.o $(mmu-y)
> > + debug.o gup.o mmap_lock.o vma_init.o $(mmu-y)
> >
> > # Give 'page_alloc' its own module-parameter namespace
> > page-alloc-y := page_alloc.o
> > diff --git a/mm/mmap.c b/mm/mmap.c
> > index 5259df031e15..81dd962a1cfc 100644
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -1554,7 +1554,7 @@ static const struct ctl_table mmap_table[] = {
> > #endif /* CONFIG_SYSCTL */
> >
> > /*
> > - * initialise the percpu counter for VM
> > + * initialise the percpu counter for VM, initialise VMA state.
> > */
> > void __init mmap_init(void)
> > {
> > @@ -1565,6 +1565,7 @@ void __init mmap_init(void)
> > #ifdef CONFIG_SYSCTL
> > register_sysctl_init("vm", mmap_table);
> > #endif
> > + vma_state_init();
> > }
> >
> > /*
> > diff --git a/mm/nommu.c b/mm/nommu.c
> > index a142fc258d39..0bf4849b8204 100644
> > --- a/mm/nommu.c
> > +++ b/mm/nommu.c
> > @@ -399,7 +399,8 @@ static const struct ctl_table nommu_table[] = {
> > };
> >
> > /*
> > - * initialise the percpu counter for VM and region record slabs
> > + * initialise the percpu counter for VM and region record slabs, initialise VMA
> > + * state.
> > */
> > void __init mmap_init(void)
> > {
> > @@ -409,6 +410,7 @@ void __init mmap_init(void)
> > VM_BUG_ON(ret);
> > vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
> > register_sysctl_init("vm", nommu_table);
> > + vma_state_init();
> > }
> >
> > /*
> > diff --git a/mm/vma.h b/mm/vma.h
> > index 94307a2e4ab6..4a1e1768ca46 100644
> > --- a/mm/vma.h
> > +++ b/mm/vma.h
> > @@ -548,8 +548,15 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address);
> >
> > int __vm_munmap(unsigned long start, size_t len, bool unlock);
> >
> > +
>
> Accidental extra line here?
>
> > int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma);
> >
> > +/* vma_init.h, shared between CONFIG_MMU and nommu. */
> > +void __init vma_state_init(void);
> > +struct vm_area_struct *vm_area_alloc(struct mm_struct *mm);
> > +struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig);
> > +void vm_area_free(struct vm_area_struct *vma);
> > +
> > /* vma_exec.h */
> > #ifdef CONFIG_MMU
> > int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap,
> > diff --git a/mm/vma_init.c b/mm/vma_init.c
> > new file mode 100644
> > index 000000000000..967ca8517986
> > --- /dev/null
> > +++ b/mm/vma_init.c
> > @@ -0,0 +1,101 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +
> > +/*
> > + * Functions for initialisaing, allocating, freeing and duplicating VMAs. Shared
> > + * between CONFIG_MMU and non-CONFIG_MMU kernel configurations.
> > + */
> > +
> > +#include "vma_internal.h"
> > +#include "vma.h"
> > +
> > +/* SLAB cache for vm_area_struct structures */
> > +static struct kmem_cache *vm_area_cachep;
> > +
> > +void __init vma_state_init(void)
> > +{
> > + struct kmem_cache_args args = {
> > + .use_freeptr_offset = true,
> > + .freeptr_offset = offsetof(struct vm_area_struct, vm_freeptr),
> > + };
> > +
> > + vm_area_cachep = kmem_cache_create("vm_area_struct",
> > + sizeof(struct vm_area_struct), &args,
> > + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
> > + SLAB_ACCOUNT);
> > +}
> > +
> > +struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
> > +{
> > + struct vm_area_struct *vma;
> > +
> > + vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
> > + if (!vma)
> > + return NULL;
> > +
> > + vma_init(vma, mm);
> > +
> > + return vma;
> > +}
> > +
> > +static void vm_area_init_from(const struct vm_area_struct *src,
> > + struct vm_area_struct *dest)
> > +{
> > + dest->vm_mm = src->vm_mm;
> > + dest->vm_ops = src->vm_ops;
> > + dest->vm_start = src->vm_start;
> > + dest->vm_end = src->vm_end;
> > + dest->anon_vma = src->anon_vma;
> > + dest->vm_pgoff = src->vm_pgoff;
> > + dest->vm_file = src->vm_file;
> > + dest->vm_private_data = src->vm_private_data;
> > + vm_flags_init(dest, src->vm_flags);
> > + memcpy(&dest->vm_page_prot, &src->vm_page_prot,
> > + sizeof(dest->vm_page_prot));
> > + /*
> > + * src->shared.rb may be modified concurrently when called from
> > + * dup_mmap(), but the clone will reinitialize it.
> > + */
> > + data_race(memcpy(&dest->shared, &src->shared, sizeof(dest->shared)));
> > + memcpy(&dest->vm_userfaultfd_ctx, &src->vm_userfaultfd_ctx,
> > + sizeof(dest->vm_userfaultfd_ctx));
> > +#ifdef CONFIG_ANON_VMA_NAME
> > + dest->anon_name = src->anon_name;
> > +#endif
> > +#ifdef CONFIG_SWAP
> > + memcpy(&dest->swap_readahead_info, &src->swap_readahead_info,
> > + sizeof(dest->swap_readahead_info));
> > +#endif
> > +#ifndef CONFIG_MMU
> > + dest->vm_region = src->vm_region;
> > +#endif
> > +#ifdef CONFIG_NUMA
> > + dest->vm_policy = src->vm_policy;
> > +#endif
> > +}
> > +
> > +struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
> > +{
> > + struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
> > +
> > + if (!new)
> > + return NULL;
> > +
> > + ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
> > + ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
> > + vm_area_init_from(orig, new);
> > + vma_lock_init(new, true);
> > + INIT_LIST_HEAD(&new->anon_vma_chain);
> > + vma_numab_state_init(new);
> > + dup_anon_vma_name(orig, new);
> > +
> > + return new;
> > +}
> > +
> > +void vm_area_free(struct vm_area_struct *vma)
> > +{
> > + /* The vma should be detached while being destroyed. */
> > + vma_assert_detached(vma);
> > + vma_numab_state_free(vma);
> > + free_anon_vma_name(vma);
> > + kmem_cache_free(vm_area_cachep, vma);
> > +}
> > diff --git a/tools/testing/vma/Makefile b/tools/testing/vma/Makefile
> > index 624040fcf193..66f3831a668f 100644
> > --- a/tools/testing/vma/Makefile
> > +++ b/tools/testing/vma/Makefile
> > @@ -9,7 +9,7 @@ include ../shared/shared.mk
> > OFILES = $(SHARED_OFILES) vma.o maple-shim.o
> > TARGETS = vma
> >
> > -vma.o: vma.c vma_internal.h ../../../mm/vma.c ../../../mm/vma_exec.c ../../../mm/vma.h
> > +vma.o: vma.c vma_internal.h ../../../mm/vma.c ../../../mm/vma_init.c ../../../mm/vma_exec.c ../../../mm/vma.h
> >
> > vma: $(OFILES)
> > $(CC) $(CFLAGS) -o $@ $(OFILES) $(LDLIBS)
> > diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c
> > index 5832ae5d797d..2be7597a2ac2 100644
> > --- a/tools/testing/vma/vma.c
> > +++ b/tools/testing/vma/vma.c
> > @@ -28,6 +28,7 @@ unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
> > * Directly import the VMA implementation here. Our vma_internal.h wrapper
> > * provides userland-equivalent functionality for everything vma.c uses.
> > */
> > +#include "../../../mm/vma_init.c"
> > #include "../../../mm/vma_exec.c"
> > #include "../../../mm/vma.c"
> >
> > @@ -91,6 +92,12 @@ static int attach_vma(struct mm_struct *mm, struct vm_area_struct *vma)
> > return res;
> > }
> >
> > +static void detach_free_vma(struct vm_area_struct *vma)
> > +{
> > + vma_mark_detached(vma);
> > + vm_area_free(vma);
> > +}
> > +
> > /* Helper function to allocate a VMA and link it to the tree. */
> > static struct vm_area_struct *alloc_and_link_vma(struct mm_struct *mm,
> > unsigned long start,
> > @@ -104,7 +111,7 @@ static struct vm_area_struct *alloc_and_link_vma(struct mm_struct *mm,
> > return NULL;
> >
> > if (attach_vma(mm, vma)) {
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > return NULL;
> > }
> >
> > @@ -249,7 +256,7 @@ static int cleanup_mm(struct mm_struct *mm, struct vma_iterator *vmi)
> >
> > vma_iter_set(vmi, 0);
> > for_each_vma(*vmi, vma) {
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > count++;
> > }
> >
> > @@ -319,7 +326,7 @@ static bool test_simple_merge(void)
> > ASSERT_EQ(vma->vm_pgoff, 0);
> > ASSERT_EQ(vma->vm_flags, flags);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > mtree_destroy(&mm.mm_mt);
> >
> > return true;
> > @@ -361,7 +368,7 @@ static bool test_simple_modify(void)
> > ASSERT_EQ(vma->vm_end, 0x1000);
> > ASSERT_EQ(vma->vm_pgoff, 0);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > vma_iter_clear(&vmi);
> >
> > vma = vma_next(&vmi);
> > @@ -370,7 +377,7 @@ static bool test_simple_modify(void)
> > ASSERT_EQ(vma->vm_end, 0x2000);
> > ASSERT_EQ(vma->vm_pgoff, 1);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > vma_iter_clear(&vmi);
> >
> > vma = vma_next(&vmi);
> > @@ -379,7 +386,7 @@ static bool test_simple_modify(void)
> > ASSERT_EQ(vma->vm_end, 0x3000);
> > ASSERT_EQ(vma->vm_pgoff, 2);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > mtree_destroy(&mm.mm_mt);
> >
> > return true;
> > @@ -407,7 +414,7 @@ static bool test_simple_expand(void)
> > ASSERT_EQ(vma->vm_end, 0x3000);
> > ASSERT_EQ(vma->vm_pgoff, 0);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > mtree_destroy(&mm.mm_mt);
> >
> > return true;
> > @@ -428,7 +435,7 @@ static bool test_simple_shrink(void)
> > ASSERT_EQ(vma->vm_end, 0x1000);
> > ASSERT_EQ(vma->vm_pgoff, 0);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > mtree_destroy(&mm.mm_mt);
> >
> > return true;
> > @@ -619,7 +626,7 @@ static bool test_merge_new(void)
> > ASSERT_EQ(vma->vm_pgoff, 0);
> > ASSERT_EQ(vma->anon_vma, &dummy_anon_vma);
> >
> > - vm_area_free(vma);
> > + detach_free_vma(vma);
> > count++;
> > }
> >
> > @@ -1668,6 +1675,7 @@ int main(void)
> > int num_tests = 0, num_fail = 0;
> >
> > maple_tree_init();
> > + vma_state_init();
> >
> > #define TEST(name) \
> > do { \
> > diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
> > index 32e990313158..198abe66de5a 100644
> > --- a/tools/testing/vma/vma_internal.h
> > +++ b/tools/testing/vma/vma_internal.h
> > @@ -155,6 +155,10 @@ typedef __bitwise unsigned int vm_fault_t;
> > */
> > #define pr_warn_once pr_err
> >
> > +#define data_race(expr) expr
> > +
> > +#define ASSERT_EXCLUSIVE_WRITER(x)
> > +
> > struct kref {
> > refcount_t refcount;
> > };
> > @@ -255,6 +259,8 @@ struct file {
> >
> > #define VMA_LOCK_OFFSET 0x40000000
> >
> > +typedef struct { unsigned long v; } freeptr_t;
> > +
> > struct vm_area_struct {
> > /* The first cache line has the info for VMA tree walking. */
> >
> > @@ -264,9 +270,7 @@ struct vm_area_struct {
> > unsigned long vm_start;
> > unsigned long vm_end;
> > };
> > -#ifdef CONFIG_PER_VMA_LOCK
> > - struct rcu_head vm_rcu; /* Used for deferred freeing. */
> > -#endif
> > + freeptr_t vm_freeptr; /* Pointer used by SLAB_TYPESAFE_BY_RCU */
> > };
> >
> > struct mm_struct *vm_mm; /* The address space we belong to. */
> > @@ -463,6 +467,65 @@ struct pagetable_move_control {
> > .len_in = len_, \
> > }
> >
> > +struct kmem_cache_args {
> > + /**
> > + * @align: The required alignment for the objects.
> > + *
> > + * %0 means no specific alignment is requested.
> > + */
> > + unsigned int align;
> > + /**
> > + * @useroffset: Usercopy region offset.
> > + *
> > + * %0 is a valid offset, when @usersize is non-%0
> > + */
> > + unsigned int useroffset;
> > + /**
> > + * @usersize: Usercopy region size.
> > + *
> > + * %0 means no usercopy region is specified.
> > + */
> > + unsigned int usersize;
> > + /**
> > + * @freeptr_offset: Custom offset for the free pointer
> > + * in &SLAB_TYPESAFE_BY_RCU caches
> > + *
> > + * By default &SLAB_TYPESAFE_BY_RCU caches place the free pointer
> > + * outside of the object. This might cause the object to grow in size.
> > + * Cache creators that have a reason to avoid this can specify a custom
> > + * free pointer offset in their struct where the free pointer will be
> > + * placed.
> > + *
> > + * Note that placing the free pointer inside the object requires the
> > + * caller to ensure that no fields are invalidated that are required to
> > + * guard against object recycling (See &SLAB_TYPESAFE_BY_RCU for
> > + * details).
> > + *
> > + * Using %0 as a value for @freeptr_offset is valid. If @freeptr_offset
> > + * is specified, %use_freeptr_offset must be set %true.
> > + *
> > + * Note that @ctor currently isn't supported with custom free pointers
> > + * as a @ctor requires an external free pointer.
> > + */
> > + unsigned int freeptr_offset;
> > + /**
> > + * @use_freeptr_offset: Whether a @freeptr_offset is used.
> > + */
> > + bool use_freeptr_offset;
> > + /**
> > + * @ctor: A constructor for the objects.
> > + *
> > + * The constructor is invoked for each object in a newly allocated slab
> > + * page. It is the cache user's responsibility to free object in the
> > + * same state as after calling the constructor, or deal appropriately
> > + * with any differences between a freshly constructed and a reallocated
> > + * object.
> > + *
> > + * %NULL means no constructor.
> > + */
> > + void (*ctor)(void *);
> > +};
> > +
> > static inline void vma_iter_invalidate(struct vma_iterator *vmi)
> > {
> > mas_pause(&vmi->mas);
> > @@ -547,31 +610,38 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
> > vma->vm_lock_seq = UINT_MAX;
> > }
> >
> > -static inline struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
> > -{
> > - struct vm_area_struct *vma = calloc(1, sizeof(struct vm_area_struct));
> > +struct kmem_cache {
> > + const char *name;
> > + size_t object_size;
> > + struct kmem_cache_args *args;
> > +};
> >
> > - if (!vma)
> > - return NULL;
> > +static inline struct kmem_cache *__kmem_cache_create(const char *name,
> > + size_t object_size,
> > + struct kmem_cache_args *args)
> > +{
> > + struct kmem_cache *ret = malloc(sizeof(struct kmem_cache));
> >
> > - vma_init(vma, mm);
> > + ret->name = name;
> > + ret->object_size = object_size;
> > + ret->args = args;
> >
> > - return vma;
> > + return ret;
> > }
> >
> > -static inline struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
> > -{
> > - struct vm_area_struct *new = calloc(1, sizeof(struct vm_area_struct));
> > +#define kmem_cache_create(__name, __object_size, __args, ...) \
> > + __kmem_cache_create((__name), (__object_size), (__args))
> >
> > - if (!new)
> > - return NULL;
> > +static inline void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
> > +{
> > + (void)gfpflags;
> >
> > - memcpy(new, orig, sizeof(*new));
> > - refcount_set(&new->vm_refcnt, 0);
> > - new->vm_lock_seq = UINT_MAX;
> > - INIT_LIST_HEAD(&new->anon_vma_chain);
> > + return calloc(s->object_size, 1);
> > +}
> >
> > - return new;
> > +static inline void kmem_cache_free(struct kmem_cache *s, void *x)
> > +{
> > + free(x);
> > }
> >
> > /*
> > @@ -738,11 +808,6 @@ static inline void mpol_put(struct mempolicy *)
> > {
> > }
> >
> > -static inline void vm_area_free(struct vm_area_struct *vma)
> > -{
> > - free(vma);
> > -}
> > -
> > static inline void lru_add_drain(void)
> > {
> > }
> > @@ -1312,4 +1377,32 @@ static inline void ksm_exit(struct mm_struct *mm)
> > (void)mm;
> > }
> >
> > +static inline void vma_lock_init(struct vm_area_struct *vma, bool reset_refcnt)
> > +{
> > + (void)vma;
> > + (void)reset_refcnt;
> > +}
> > +
> > +static inline void vma_numab_state_init(struct vm_area_struct *vma)
> > +{
> > + (void)vma;
> > +}
> > +
> > +static inline void vma_numab_state_free(struct vm_area_struct *vma)
> > +{
> > + (void)vma;
> > +}
> > +
> > +static inline void dup_anon_vma_name(struct vm_area_struct *orig_vma,
> > + struct vm_area_struct *new_vma)
> > +{
> > + (void)orig_vma;
> > + (void)new_vma;
> > +}
> > +
> > +static inline void free_anon_vma_name(struct vm_area_struct *vma)
> > +{
> > + (void)vma;
> > +}
> > +
> > #endif /* __MM_VMA_INTERNAL_H */
> > --
> > 2.49.0
> >
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