From nobody Fri Jun 12 19:58:08 2026 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D4281386428; Wed, 13 May 2026 02:52:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778640726; cv=none; b=WHJr+ING1Zzdm6hi2YgmMsFIjLnxXdM07JrdeBJb2OueWGXmg/spDWqbH+de8v8KmKJA+OLFj34vBZXPcYwn/4VZ1CcA5iKBEARnpm48Xkysv79u5I8tOdUxmpIKFA+TlFgSg2lz0KiM8gsAFlUHHKAKrHGOXMQiSuvuDB3ftMo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778640726; c=relaxed/simple; bh=kx0r2cMTgAbfxeBvwsLNQsneUYNWcSWMOH9u65lbEkM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=eUjKVV0i0d7NjYEQpzs/pF0dVogn4zKpEkEFLikIaA8z3yYEydapoH4YEuSG/mhJKperswjPWdo8NmmUmhCVtsAjbU1S2hauLpeNWwnY9mCRp+gBNl6WoEsRL9JrVSso0mfIBU0geOap3peXOx3+ieyR9waWLQvYhR5qtv0b7Ok= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: b501b84c4e7611f1aa26b74ffac11d73-20260513 X-CTIC-Tags: HR_CC_COUNT, HR_CC_DOMAIN_COUNT, HR_CC_NAME, HR_CC_NO_NAME, HR_CTE_8B HR_CTT_MISS, HR_DATE_H, HR_DATE_WKD, HR_DATE_ZONE, HR_FROM_NAME HR_SJ_LANG, HR_SJ_LEN, HR_SJ_LETTER, HR_SJ_NOR_SYM, HR_SJ_PHRASE HR_SJ_PHRASE_LEN, HR_SJ_WS, HR_TO_COUNT, HR_TO_DOMAIN_COUNT, HR_TO_NO_NAME IP_TRUSTED, SRC_TRUSTED, DN_TRUSTED, SA_TRUSTED, SA_EXISTED SN_TRUSTED, SN_EXISTED, SPF_NOPASS, DKIM_NOPASS, DMARC_NOPASS CIE_GOOD, CIE_GOOD_SPF, GTI_FG_BS, GTI_RG_INFO, GTI_C_BU AMN_GOOD, ABX_MISS_RDNS X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.12,REQID:3893ce71-eea7-4218-96bc-e0da04ff880c,IP:10, URL:0,TC:0,Content:0,EDM:0,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTIO N:release,TS:5 X-CID-INFO: VERSION:1.3.12,REQID:3893ce71-eea7-4218-96bc-e0da04ff880c,IP:10,UR L:0,TC:0,Content:0,EDM:0,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:5 X-CID-META: VersionHash:e7bac3a,CLOUDID:0bf957cb8a3a83ac8a9446aead074fd4,BulkI D:2605131051584BNAGW4A,BulkQuantity:0,Recheck:0,SF:17|19|38|66|78|102|127| 850|898,TC:nil,Content:0|15|50,EDM:-3,IP:-2,URL:0,File:nil,RT:nil,Bulk:nil ,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE: 0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR,TF_CID_SPAM_FAS,TF_CID_SPAM_FSD X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: b501b84c4e7611f1aa26b74ffac11d73-20260513 X-User: lihongfu@kylinos.cn Received: from localhost.localdomain [(223.70.159.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 806173697; Wed, 13 May 2026 10:51:57 +0800 From: Hongfu Li To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hongfu Li Subject: [PATCH] selftests/mm: Fix incorrect mmap() error handling with NULL instead of MAP_FAILED Date: Wed, 13 May 2026 10:52:23 +0800 Message-Id: <20260513025223.592766-1-lihongfu@kylinos.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" mmap() returns MAP_FAILED, which is defined as (void *)-1, on error, not NULL. Several selftests incorrectly check the return value of mmap() using !ptr or ptr =3D=3D NULL, which would erroneously treat MAP_FAILED as a valid pointer since MAP_FAILED is non-zero and non-NULL. This can lead to segfaults when mmap() actually fails under memory pressure. Signed-off-by: Hongfu Li Reviewed-by: Dev Jain Reviewed-by: Lorenzo Stoakes --- tools/testing/selftests/mm/ksm_tests.c | 2 +- tools/testing/selftests/mm/madv_populate.c | 2 +- tools/testing/selftests/mm/soft-dirty.c | 4 ++-- tools/testing/selftests/mm/vm_util.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftes= ts/mm/ksm_tests.c index a0b48b839d54..ed481f817282 100644 --- a/tools/testing/selftests/mm/ksm_tests.c +++ b/tools/testing/selftests/mm/ksm_tests.c @@ -174,7 +174,7 @@ static void *allocate_memory(void *ptr, int prot, int = mapping, char data, size_ { void *map_ptr =3D mmap(ptr, map_size, PROT_WRITE, mapping, -1, 0); =20 - if (!map_ptr) { + if (map_ptr =3D=3D MAP_FAILED) { perror("mmap"); return NULL; } diff --git a/tools/testing/selftests/mm/madv_populate.c b/tools/testing/sel= ftests/mm/madv_populate.c index 88050e0f829a..7fce5d0b622b 100644 --- a/tools/testing/selftests/mm/madv_populate.c +++ b/tools/testing/selftests/mm/madv_populate.c @@ -34,7 +34,7 @@ static void sense_support(void) =20 addr =3D mmap(0, pagesize, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); - if (!addr) + if (addr =3D=3D MAP_FAILED) ksft_exit_fail_msg("mmap failed\n"); =20 ret =3D madvise(addr, pagesize, MADV_POPULATE_READ); diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selfte= sts/mm/soft-dirty.c index bcfcac99b436..67c26c265880 100644 --- a/tools/testing/selftests/mm/soft-dirty.c +++ b/tools/testing/selftests/mm/soft-dirty.c @@ -143,7 +143,7 @@ static void test_mprotect(int pagemap_fd, int pagesize,= bool anon) if (anon) { map =3D mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); - if (!map) + if (map =3D=3D MAP_FAILED) ksft_exit_fail_msg("anon mmap failed\n"); } else { test_fd =3D open(fname, O_RDWR | O_CREAT, 0664); @@ -155,7 +155,7 @@ static void test_mprotect(int pagemap_fd, int pagesize,= bool anon) ftruncate(test_fd, pagesize); map =3D mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_SHARED, test_fd, 0); - if (!map) + if (map =3D=3D MAP_FAILED) ksft_exit_fail_msg("file mmap failed\n"); } =20 diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests= /mm/vm_util.c index db94564f4431..63aaa2d9ec0b 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -463,7 +463,7 @@ bool softdirty_supported(void) /* New mappings are expected to be marked with VM_SOFTDIRTY (sd). */ addr =3D mmap(0, pagesize, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); - if (!addr) + if (addr =3D=3D MAP_FAILED) ksft_exit_fail_msg("mmap failed\n"); =20 supported =3D check_vmflag(addr, "sd"); --=20 2.25.1