NothingOSS/android_kernel_msm-6.1_nothing_sm7635
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UPSTREAM: mm: rcu safe VMA freeing

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This prepares for page faults handling under VMA lock, looking up VMAs
under protection of an rcu read lock, instead of the usual mmap read lock.

Link: https://lkml.kernel.org/r/20230227173632.3292573-11-surenb@google.com
Signed-off-by: Michel Lespinasse <michel@lespinasse.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 20cce633f4254cc0df39665449726e3172518f6c)

Bug: 161210518
Change-Id: Ic1262d00de9dc84ed2cc506b3bae7ef714efdfaa
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Michel Lespinasse 2023-02-27 09:36:09 -08:00 • committed by Carlos Llamas
parent 04f73ad5b4
commit e28a0a0e5c
2 changed files with 29 additions and 4 deletions
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13
include/linux/mm_types.h
View file

@ -445,9 +445,16 @@ struct anon_vma_name {
struct vm_area_struct {
/* The first cache line has the info for VMA tree walking. */
unsigned long vm_start; /* Our start address within vm_mm. */
unsigned long vm_end; /* The first byte after our end address
within vm_mm. */
union {
struct {
/* VMA covers [vm_start; vm_end) addresses within mm */
unsigned long vm_start;
unsigned long vm_end;
};
#ifdef CONFIG_PER_VMA_LOCK
struct rcu_head vm_rcu; /* Used for deferred freeing. */
#endif
};
struct mm_struct *vm_mm; /* The address space we belong to. */

20
kernel/fork.c
View file

@ -486,12 +486,30 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
return new;
}
void vm_area_free(struct vm_area_struct *vma)
static void __vm_area_free(struct vm_area_struct *vma)
{
free_anon_vma_name(vma);
kmem_cache_free(vm_area_cachep, vma);
}
#ifdef CONFIG_PER_VMA_LOCK
static void vm_area_free_rcu_cb(struct rcu_head *head)
{
struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
vm_rcu);
__vm_area_free(vma);
}
#endif
void vm_area_free(struct vm_area_struct *vma)
{
#ifdef CONFIG_PER_VMA_LOCK
call_rcu(&vma->vm_rcu, vm_area_free_rcu_cb);
#else
__vm_area_free(vma);
#endif
}
static void account_kernel_stack(struct task_struct *tsk, int account)
{
if (IS_ENABLED(CONFIG_VMAP_STACK)) {