mm/page_owner: Simplify stack trace handling

Replace the indirection through struct stack_trace by using the storage
array based interfaces.

The original code in all printing functions is really wrong. It allocates a
storage array on stack which is unused because depot_fetch_stack() does not
store anything in it. It overwrites the entries pointer in the stack_trace
struct so it points to the depot storage.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: linux-mm@kvack.org
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094802.067210525@linutronix.de

1 files changed, 28 insertions, 51 deletions

diff --git a/mm/page_owner.c b/mm/page_owner.c
index df277e6bc3c6..addcbb2ae4e4 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -58,15 +58,10 @@ static bool need_page_owner(void)
 static __always_inline depot_stack_handle_t create_dummy_stack(void)
 {
         unsigned long entries[4];
-        struct stack_trace dummy;
+        unsigned int nr_entries;
 
-        dummy.nr_entries = 0;
-        dummy.max_entries = ARRAY_SIZE(entries);
-        dummy.entries = &entries[0];
-        dummy.skip = 0;
-
-        save_stack_trace(&dummy);
-        return depot_save_stack(&dummy, GFP_KERNEL);
+        nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
+        return stack_depot_save(entries, nr_entries, GFP_KERNEL);
 }
 
 static noinline void register_dummy_stack(void)
@@ -120,46 +115,39 @@ void __reset_page_owner(struct page *page, unsigned int order)
         }
 }
 
-static inline bool check_recursive_alloc(struct stack_trace *trace,
-                                        unsigned long ip)
+static inline bool check_recursive_alloc(unsigned long *entries,
+                                         unsigned int nr_entries,
+                                         unsigned long ip)
 {
-        int i;
-
-        if (!trace->nr_entries)
-                return false;
+        unsigned int i;
 
-        for (i = 0; i < trace->nr_entries; i++) {
-                if (trace->entries[i] == ip)
+        for (i = 0; i < nr_entries; i++) {
+                if (entries[i] == ip)
                         return true;
         }
-
         return false;
 }
 
 static noinline depot_stack_handle_t save_stack(gfp_t flags)
 {
         unsigned long entries[PAGE_OWNER_STACK_DEPTH];
-        struct stack_trace trace = {
-                .nr_entries = 0,
-                .entries = entries,
-                .max_entries = PAGE_OWNER_STACK_DEPTH,
-                .skip = 2
-        };
         depot_stack_handle_t handle;
+        unsigned int nr_entries;
 
-        save_stack_trace(&trace);
+        nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
 
         /*
-         * We need to check recursion here because our request to stackdepot
-         * could trigger memory allocation to save new entry. New memory
-         * allocation would reach here and call depot_save_stack() again
-         * if we don't catch it. There is still not enough memory in stackdepot
-         * so it would try to allocate memory again and loop forever.
+         * We need to check recursion here because our request to
+         * stackdepot could trigger memory allocation to save new
+         * entry. New memory allocation would reach here and call
+         * stack_depot_save_entries() again if we don't catch it. There is
+         * still not enough memory in stackdepot so it would try to
+         * allocate memory again and loop forever.
          */
-        if (check_recursive_alloc(&trace, _RET_IP_))
+        if (check_recursive_alloc(entries, nr_entries, _RET_IP_))
                 return dummy_handle;
 
-        handle = depot_save_stack(&trace, flags);
+        handle = stack_depot_save(entries, nr_entries, flags);
         if (!handle)
                 handle = failure_handle;
 
@@ -337,16 +325,10 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
                 struct page *page, struct page_owner *page_owner,
                 depot_stack_handle_t handle)
 {
-        int ret;
-        int pageblock_mt, page_mt;
+        int ret, pageblock_mt, page_mt;
+        unsigned long *entries;
+        unsigned int nr_entries;
         char *kbuf;
-        unsigned long entries[PAGE_OWNER_STACK_DEPTH];
-        struct stack_trace trace = {
-                .nr_entries = 0,
-                .entries = entries,
-                .max_entries = PAGE_OWNER_STACK_DEPTH,
-                .skip = 0
-        };
 
         count = min_t(size_t, count, PAGE_SIZE);
         kbuf = kmalloc(count, GFP_KERNEL);
@@ -375,8 +357,8 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
         if (ret >= count)
                 goto err;
 
-        depot_fetch_stack(handle, &trace);
-        ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
+        nr_entries = stack_depot_fetch(handle, &entries);
+        ret += stack_trace_snprint(kbuf + ret, count - ret, entries, nr_entries, 0);
         if (ret >= count)
                 goto err;
 
@@ -407,14 +389,9 @@ void __dump_page_owner(struct page *page)
 {
         struct page_ext *page_ext = lookup_page_ext(page);
         struct page_owner *page_owner;
-        unsigned long entries[PAGE_OWNER_STACK_DEPTH];
-        struct stack_trace trace = {
-                .nr_entries = 0,
-                .entries = entries,
-                .max_entries = PAGE_OWNER_STACK_DEPTH,
-                .skip = 0
-        };
         depot_stack_handle_t handle;
+        unsigned long *entries;
+        unsigned int nr_entries;
         gfp_t gfp_mask;
         int mt;
 
@@ -438,10 +415,10 @@ void __dump_page_owner(struct page *page)
                 return;
         }
 
-        depot_fetch_stack(handle, &trace);
+        nr_entries = stack_depot_fetch(handle, &entries);
         pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n",
                  page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask);
-        print_stack_trace(&trace, 0);
+        stack_trace_print(entries, nr_entries, 0);
 
         if (page_owner->last_migrate_reason != -1)
                 pr_alert("page has been migrated, last migrate reason: %s\n",