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Message-Id: <20190410103645.951691679@linutronix.de> Date: Wed, 10 Apr 2019 12:28:20 +0200 From: Thomas Gleixner <tglx@...utronix.de> To: LKML <linux-kernel@...r.kernel.org> Cc: Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org, Andy Lutomirski <luto@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, Alexander Potapenko <glider@...gle.com>, linux-mm@...ck.org, Mike Rapoport <rppt@...ux.vnet.ibm.com>, David Rientjes <rientjes@...gle.com>, Andrew Morton <akpm@...ux-foundation.org> Subject: [RFC patch 26/41] 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@...utronix.de> Cc: linux-mm@...ck.org Cc: Mike Rapoport <rppt@...ux.vnet.ibm.com> Cc: David Rientjes <rientjes@...gle.com> Cc: Andrew Morton <akpm@...ux-foundation.org> --- mm/page_owner.c | 79 +++++++++++++++++++------------------------------------- 1 file changed, 28 insertions(+), 51 deletions(-) --- 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 nent; - 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); + nent = stack_trace_save(entries, ARRAY_SIZE(entries), 0); + return stack_depot_save(entries, nent, GFP_KERNEL); } static noinline void register_dummy_stack(void) @@ -120,46 +115,39 @@ void __reset_page_owner(struct page *pag } } -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; + unsigned int i; - if (!trace->nr_entries) - return false; - - 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 nent; - save_stack_trace(&trace); + nent = 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, nent, _RET_IP_)) return dummy_handle; - handle = depot_save_stack(&trace, flags); + handle = stack_depot_save(entries, nent, flags); if (!handle) handle = failure_handle; @@ -337,16 +325,10 @@ print_page_owner(char __user *buf, size_ 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 nent; 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_ if (ret >= count) goto err; - depot_fetch_stack(handle, &trace); - ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0); + nent = stack_depot_fetch(handle, &entries); + ret += stack_trace_snprint(kbuf + ret, count - ret, entries, nent, 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 nent; gfp_t gfp_mask; int mt; @@ -438,10 +415,10 @@ void __dump_page_owner(struct page *page return; } - depot_fetch_stack(handle, &trace); + nent = 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, nent, 0); if (page_owner->last_migrate_reason != -1) pr_alert("page has been migrated, last migrate reason: %s\n",
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