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Commit af52bf6b authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarJosh 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
parent 880e049c

mm/page_owner.c

+28 −51
Original line number Diff line number Diff line
@@ -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,

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",