From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 1/5] mm/z3fold: silence kmemleak false positives of slots Date: Wed, 27 May 2020 22:20:40 -0700 Message-ID: <20200528052040.tET7TeyHc%akpm@linux-foundation.org> References: <20200527222015.62ba8592af63dae12ab58ffe@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:45166 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725764AbgE1FUm (ORCPT ); Thu, 28 May 2020 01:20:42 -0400 In-Reply-To: <20200527222015.62ba8592af63dae12ab58ffe@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, cai@lca.pw, catalin.marinas@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, vitaly.wool@konsulko.com From: Qian Cai Subject: mm/z3fold: silence kmemleak false positives of slots Kmemleak reported many leaks while under memory pressue in, slots = alloc_slots(pool, gfp); which is referenced by "zhdr" in init_z3fold_page(), zhdr->slots = slots; However, "zhdr" could be gone without freeing slots as the later will be freed separately when the last "handle" off of "handles" array is freed. It will be within "slots" which is always aligned. unreferenced object 0xc000000fdadc1040 (size 104): comm "oom04", pid 140476, jiffies 4295359280 (age 3454.970s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000d1f0f5eb>] z3fold_zpool_malloc+0x7b0/0xe10 alloc_slots at mm/z3fold.c:214 (inlined by) init_z3fold_page at mm/z3fold.c:412 (inlined by) z3fold_alloc at mm/z3fold.c:1161 (inlined by) z3fold_zpool_malloc at mm/z3fold.c:1735 [<0000000064a2e969>] zpool_malloc+0x34/0x50 [<00000000af63e491>] zswap_frontswap_store+0x60c/0xda0 zswap_frontswap_store at mm/zswap.c:1093 [<00000000af5e07e0>] __frontswap_store+0x128/0x330 [<00000000de2f582b>] swap_writepage+0x58/0x110 [<000000000120885f>] pageout+0x16c/0xa40 [<00000000444c1f68>] shrink_page_list+0x1ac8/0x25c0 [<00000000d19e8610>] shrink_inactive_list+0x270/0x730 [<00000000e17df726>] shrink_lruvec+0x444/0xf30 [<000000005f02ab35>] shrink_node+0x2a4/0x9c0 [<00000000014cabbd>] do_try_to_free_pages+0x158/0x640 [<00000000dcfaba07>] try_to_free_pages+0x1bc/0x5f0 [<00000000fa207ab8>] __alloc_pages_slowpath.constprop.60+0x4dc/0x15a0 [<000000003669f1d2>] __alloc_pages_nodemask+0x520/0x650 [<0000000011fa4168>] alloc_pages_vma+0xc0/0x420 [<0000000098b376f2>] handle_mm_fault+0x1174/0x1bf0 Link: http://lkml.kernel.org/r/20200522220052.2225-1-cai@lca.pw Signed-off-by: Qian Cai Acked-by: Vitaly Wool Acked-by: Catalin Marinas Signed-off-by: Andrew Morton --- mm/z3fold.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/z3fold.c~mm-z3fold-silence-kmemleak-false-positives-of-slots +++ a/mm/z3fold.c @@ -43,6 +43,7 @@ #include #include #include +#include /* * NCHUNKS_ORDER determines the internal allocation granularity, effectively @@ -215,6 +216,8 @@ static inline struct z3fold_buddy_slots (gfp & ~(__GFP_HIGHMEM | __GFP_MOVABLE))); if (slots) { + /* It will be freed separately in free_handle(). */ + kmemleak_not_leak(slots); memset(slots->slot, 0, sizeof(slots->slot)); slots->pool = (unsigned long)pool; rwlock_init(&slots->lock); _