[PATCH v2 31/39] mm: percpu: enable per-cpu allocation tagging

Suren Baghdasaryan
2023-10-24T13:48:27Z

Redefine __alloc_percpu, __alloc_percpu_gfp and __alloc_reserved_percpu
to record allocations and deallocations done by these functions.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
include/linux/alloc_tag.h | 15 +++++++++
include/linux/percpu.h | 23 +++++++++-----
mm/percpu.c | 64 +++++----------------------------------
3 files changed, 38 insertions(+), 64 deletions(-)

diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
index 6fa8a94d8bc1..3fe51e67e231 100644
--- a/include/linux/alloc_tag.h
+++ b/include/linux/alloc_tag.h
@@ -140,4 +140,19 @@ static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_tag *tag,
_res; \
})

+/*
+ * workaround for a sparse bug: it complains about res_type_to_err() when
+ * typeof(_do_alloc) is a __percpu pointer, but gcc won't let us add a separate
+ * __percpu case to res_type_to_err():
+ */
+#define alloc_hooks_pcpu(_do_alloc) \
+({ \
+ typeof(_do_alloc) _res; \
+ DEFINE_ALLOC_TAG(_alloc_tag, _old); \
+ \
+ _res = _do_alloc; \
+ alloc_tag_restore(&_alloc_tag, _old); \
+ _res; \
+})
+
#endif /* _LINUX_ALLOC_TAG_H */
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 68fac2e7cbe6..338c1ef9c93d 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -2,6 +2,7 @@
#ifndef __LINUX_PERCPU_H
#define __LINUX_PERCPU_H

+#include <linux/alloc_tag.h>
#include <linux/mmdebug.h>
#include <linux/preempt.h>
#include <linux/smp.h>
@@ -9,6 +10,7 @@
#include <linux/pfn.h>
#include <linux/init.h>
#include <linux/cleanup.h>
+#include <linux/sched.h>

#include <asm/percpu.h>

@@ -121,7 +123,6 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn);
#endif

-extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align) __alloc_size(1);
extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
extern bool is_kernel_percpu_address(unsigned long addr);

@@ -129,13 +130,15 @@ extern bool is_kernel_percpu_address(unsigned long addr);
extern void __init setup_per_cpu_areas(void);
#endif

-extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) __alloc_size(1);
-extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_size(1);
-extern void free_percpu(void __percpu *__pdata);
+extern void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
+ gfp_t gfp) __alloc_size(1);

-DEFINE_FREE(free_percpu, void __percpu *, free_percpu(_T))
-
-extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
+#define __alloc_percpu_gfp(_size, _align, _gfp) \
+ alloc_hooks_pcpu(pcpu_alloc_noprof(_size, _align, false, _gfp))
+#define __alloc_percpu(_size, _align) \
+ alloc_hooks_pcpu(pcpu_alloc_noprof(_size, _align, false, GFP_KERNEL))
+#define __alloc_reserved_percpu(_size, _align) \
+ alloc_hooks_pcpu(pcpu_alloc_noprof(_size, _align, true, GFP_KERNEL))

#define alloc_percpu_gfp(type, gfp) \
(typeof(type) __percpu *)__alloc_percpu_gfp(sizeof(type), \
@@ -144,6 +147,12 @@ extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
(typeof(type) __percpu *)__alloc_percpu(sizeof(type), \
__alignof__(type))

+extern void free_percpu(void __percpu *__pdata);
+
+DEFINE_FREE(free_percpu, void __percpu *, free_percpu(_T))
+
+extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
+
extern unsigned long pcpu_nr_pages(void);

#endif /* __LINUX_PERCPU_H */
diff --git a/mm/percpu.c b/mm/percpu.c
index 002ee5d38fd5..328a5b3c943b 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1728,7 +1728,7 @@ static void pcpu_alloc_tag_free_hook(struct pcpu_chunk *chunk, int off, size_t s
#endif

/**
- * pcpu_alloc - the percpu allocator
+ * pcpu_alloc_noprof - the percpu allocator
* @size: size of area to allocate in bytes
* @align: alignment of area (max PAGE_SIZE)
* @reserved: allocate from the reserved chunk if available
@@ -1742,7 +1742,7 @@ static void pcpu_alloc_tag_free_hook(struct pcpu_chunk *chunk, int off, size_t s
* RETURNS:
* Percpu pointer to the allocated area on success, NULL on failure.
*/
-static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
+void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
gfp_t gfp)
{
gfp_t pcpu_gfp;
@@ -1909,6 +1909,8 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,

pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);

+ pcpu_alloc_tag_alloc_hook(chunk, off, size);
+
return ptr;

fail_unlock:
@@ -1937,61 +1939,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,

return NULL;
}
-
-/**
- * __alloc_percpu_gfp - allocate dynamic percpu area
- * @size: size of area to allocate in bytes
- * @align: alignment of area (max PAGE_SIZE)
- * @gfp: allocation flags
- *
- * Allocate zero-filled percpu area of @size bytes aligned at @align. If
- * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
- * be called from any context but is a lot more likely to fail. If @gfp
- * has __GFP_NOWARN then no warning will be triggered on invalid or failed
- * allocation requests.
- *
- * RETURNS:
- * Percpu pointer to the allocated area on success, NULL on failure.
- */
-void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
-{
- return pcpu_alloc(size, align, false, gfp);
-}
-EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
-
-/**
- * __alloc_percpu - allocate dynamic percpu area
- * @size: size of area to allocate in bytes
- * @align: alignment of area (max PAGE_SIZE)
- *
- * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
- */
-void __percpu *__alloc_percpu(size_t size, size_t align)
-{
- return pcpu_alloc(size, align, false, GFP_KERNEL);
-}
-EXPORT_SYMBOL_GPL(__alloc_percpu);
-
-/**
- * __alloc_reserved_percpu - allocate reserved percpu area
- * @size: size of area to allocate in bytes
- * @align: alignment of area (max PAGE_SIZE)
- *
- * Allocate zero-filled percpu area of @size bytes aligned at @align
- * from reserved percpu area if arch has set it up; otherwise,
- * allocation is served from the same dynamic area. Might sleep.
- * Might trigger writeouts.
- *
- * CONTEXT:
- * Does GFP_KERNEL allocation.
- *
- * RETURNS:
- * Percpu pointer to the allocated area on success, NULL on failure.
- */
-void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
-{
- return pcpu_alloc(size, align, true, GFP_KERNEL);
-}
+EXPORT_SYMBOL_GPL(pcpu_alloc_noprof);

/**
* pcpu_balance_free - manage the amount of free chunks
@@ -2301,6 +2249,8 @@ void free_percpu(void __percpu *ptr)

size = pcpu_free_area(chunk, off);

+ pcpu_alloc_tag_free_hook(chunk, off, size);
+
pcpu_memcg_free_hook(chunk, off, size);

/*
--
2.42.0.758.gaed0368e0e-goog