[PATCH v2 09/33] mm: rcu safe VMA freeing
From: Suren Baghdasaryan <surenb@google.com>
Date: 2023-01-27 19:43:33
Also in:
linux-mm, linuxppc-dev, lkml
Subsystem:
exec & binfmt api, elf, memory management - core, scheduler, the rest · Maintainers:
Kees Cook, Andrew Morton, David Hildenbrand, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
From: Michel Lespinasse <redacted> 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. Signed-off-by: Michel Lespinasse <redacted> Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- include/linux/mm_types.h | 13 ++++++++++--- kernel/fork.c | 20 +++++++++++++++++++- 2 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8410c3052148..62e413f84011 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h@@ -480,9 +480,16 @@ 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. */
diff --git a/kernel/fork.c b/kernel/fork.c
index 5f23d5e03362..314d51eb91da 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c@@ -479,12 +479,30 @@ 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)) {
--
2.39.1
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