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Revert "mm: protect mm_rb tree with a rwlock"

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This reverts commit 3f31f748a8.

Signed-off-by: UtsavBalar1231 <utsavbalar1231@gmail.com>
Change-Id: I1a40b5e06288d7eb1448a98494f0fe6d2949d129
This commit is contained in:
UtsavBalar1231 2022-04-28 19:16:21 +05:30 committed by spakkkk
parent a56e9d538b
commit 568b2f7bf3
6 changed files with 28 additions and 104 deletions
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1
include/linux/mm.h
View File

@ -481,7 +481,6 @@ static inline void INIT_VMA(struct vm_area_struct *vma)
INIT_LIST_HEAD(&vma->anon_vma_chain);
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
seqcount_init(&vma->vm_sequence);
atomic_set(&vma->vm_ref_count, 1);
#endif
}

4
include/linux/mm_types.h
View File

@ -338,7 +338,6 @@ struct vm_area_struct {
struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
seqcount_t vm_sequence; /* Speculative page fault field */
atomic_t vm_ref_count; /* see vma_get(), vma_put() */
#endif
ANDROID_KABI_RESERVE(1);
@ -364,9 +363,6 @@ struct mm_struct {
struct vm_area_struct *mmap; /* list of VMAs */
struct rb_root mm_rb;
u64 vmacache_seqnum; /* per-thread vmacache */
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
rwlock_t mm_rb_lock; /* Speculative page fault field */
#endif
#ifdef CONFIG_MMU
unsigned long (*get_unmapped_area) (struct file *filp,
unsigned long addr, unsigned long len,

3
kernel/fork.c
View File

@ -988,9 +988,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
mm->mmap = NULL;
mm->mm_rb = RB_ROOT;
mm->vmacache_seqnum = 0;
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
rwlock_init(&mm->mm_rb_lock);
#endif
atomic_set(&mm->mm_users, 1);
atomic_set(&mm->mm_count, 1);
init_rwsem(&mm->mmap_sem);

3
mm/init-mm.c
View File

@ -27,9 +27,6 @@
*/
struct mm_struct init_mm = {
.mm_rb = RB_ROOT,
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
.mm_rb_lock = __RW_LOCK_UNLOCKED(init_mm.mm_rb_lock),
#endif
.pgd = swapper_pg_dir,
.mm_users = ATOMIC_INIT(2),
.mm_count = ATOMIC_INIT(1),

6
mm/internal.h
View File

@ -40,12 +40,6 @@ void page_writeback_init(void);
vm_fault_t do_swap_page(struct vm_fault *vmf);
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
extern struct vm_area_struct *get_vma(struct mm_struct *mm,
unsigned long addr);
extern void put_vma(struct vm_area_struct *vma);
#endif
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
unsigned long floor, unsigned long ceiling);

115
mm/mmap.c
View File

@ -164,27 +164,6 @@ void unlink_file_vma(struct vm_area_struct *vma)
}
}
static void __free_vma(struct vm_area_struct *vma)
{
if (vma->vm_file)
fput(vma->vm_file);
mpol_put(vma_policy(vma));
vm_area_free(vma);
}
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
void put_vma(struct vm_area_struct *vma)
{
if (atomic_dec_and_test(&vma->vm_ref_count))
__free_vma(vma);
}
#else
static inline void put_vma(struct vm_area_struct *vma)
{
__free_vma(vma);
}
#endif
/*
* Close a vm structure and free it, returning the next.
*/
@ -195,7 +174,10 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
might_sleep();
if (vma->vm_ops && vma->vm_ops->close)
vma->vm_ops->close(vma);
put_vma(vma);
if (vma->vm_file)
fput(vma->vm_file);
mpol_put(vma_policy(vma));
vm_area_free(vma);
return next;
}
@ -415,14 +397,6 @@ static void validate_mm(struct mm_struct *mm)
#define validate_mm(mm) do { } while (0)
#endif
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
#define mm_rb_write_lock(mm) write_lock(&(mm)->mm_rb_lock)
#define mm_rb_write_unlock(mm) write_unlock(&(mm)->mm_rb_lock)
#else
#define mm_rb_write_lock(mm) do { } while (0)
#define mm_rb_write_unlock(mm) do { } while (0)
#endif /* CONFIG_SPECULATIVE_PAGE_FAULT */
RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
@ -441,37 +415,26 @@ static void vma_gap_update(struct vm_area_struct *vma)
}
static inline void vma_rb_insert(struct vm_area_struct *vma,
struct mm_struct *mm)
struct rb_root *root)
{
struct rb_root *root = &mm->mm_rb;
/* All rb_subtree_gap values must be consistent prior to insertion */
validate_mm_rb(root, NULL);
rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
}
static void __vma_rb_erase(struct vm_area_struct *vma, struct mm_struct *mm)
static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
{
struct rb_root *root = &mm->mm_rb;
/*
* Note rb_erase_augmented is a fairly large inline function,
* so make sure we instantiate it only once with our desired
* augmented rbtree callbacks.
*/
mm_rb_write_lock(mm);
rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
mm_rb_write_unlock(mm); /* wmb */
/*
* Ensure the removal is complete before clearing the node.
* Matched by vma_has_changed()/handle_speculative_fault().
*/
RB_CLEAR_NODE(&vma->vm_rb);
}
static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
struct mm_struct *mm,
struct rb_root *root,
struct vm_area_struct *ignore)
{
/*
@ -479,21 +442,21 @@ static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
* with the possible exception of the "next" vma being erased if
* next->vm_start was reduced.
*/
validate_mm_rb(&mm->mm_rb, ignore);
validate_mm_rb(root, ignore);
__vma_rb_erase(vma, mm);
__vma_rb_erase(vma, root);
}
static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
struct mm_struct *mm)
struct rb_root *root)
{
/*
* All rb_subtree_gap values must be consistent prior to erase,
* with the possible exception of the vma being erased.
*/
validate_mm_rb(&mm->mm_rb, vma);
validate_mm_rb(root, vma);
__vma_rb_erase(vma, mm);
__vma_rb_erase(vma, root);
}
/*
@ -608,12 +571,10 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
* immediately update the gap to the correct value. Finally we
* rebalance the rbtree after all augmented values have been set.
*/
mm_rb_write_lock(mm);
rb_link_node(&vma->vm_rb, rb_parent, rb_link);
vma->rb_subtree_gap = 0;
vma_gap_update(vma);
vma_rb_insert(vma, mm);
mm_rb_write_unlock(mm);
vma_rb_insert(vma, &mm->mm_rb);
}
static void __vma_link_file(struct vm_area_struct *vma)
@ -689,7 +650,7 @@ static __always_inline void __vma_unlink_common(struct mm_struct *mm,
{
struct vm_area_struct *next;
vma_rb_erase_ignore(vma, mm, ignore);
vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
next = vma->vm_next;
if (has_prev)
prev->vm_next = next;
@ -946,13 +907,16 @@ again:
}
if (remove_next) {
if (file)
if (file) {
uprobe_munmap(next, next->vm_start, next->vm_end);
fput(file);
}
if (next->anon_vma)
anon_vma_merge(vma, next);
mm->map_count--;
mpol_put(vma_policy(next));
vm_write_end(next);
put_vma(next);
vm_area_free(next);
/*
* In mprotect's case 6 (see comments on vma_merge),
* we must remove another next too. It would clutter
@ -2261,11 +2225,15 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
EXPORT_SYMBOL(get_unmapped_area);
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
static struct vm_area_struct *__find_vma(struct mm_struct *mm,
unsigned long addr)
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
struct rb_node *rb_node;
struct vm_area_struct *vma = NULL;
struct vm_area_struct *vma;
/* Check the cache first. */
vma = vmacache_find(mm, addr);
if (likely(vma))
return vma;
rb_node = mm->mm_rb.rb_node;
@ -2283,40 +2251,13 @@ static struct vm_area_struct *__find_vma(struct mm_struct *mm,
rb_node = rb_node->rb_right;
}
return vma;
}
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma;
/* Check the cache first. */
vma = vmacache_find(mm, addr);
if (likely(vma))
return vma;
vma = __find_vma(mm, addr);
if (vma)
vmacache_update(addr, vma);
return vma;
}
EXPORT_SYMBOL(find_vma);
#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
struct vm_area_struct *get_vma(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma = NULL;
read_lock(&mm->mm_rb_lock);
vma = __find_vma(mm, addr);
if (vma)
atomic_inc(&vma->vm_ref_count);
read_unlock(&mm->mm_rb_lock);
return vma;
}
#endif
/*
* Same as find_vma, but also return a pointer to the previous VMA in *pprev.
*/
@ -2704,7 +2645,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
insertion_point = (prev ? &prev->vm_next : &mm->mmap);
vma->vm_prev = NULL;
do {
vma_rb_erase(vma, mm);
vma_rb_erase(vma, &mm->mm_rb);
mm->map_count--;
tail_vma = vma;
vma = vma->vm_next;