From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79669C46CD2 for ; Wed, 24 Jan 2024 07:03:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 12B006B0075; Wed, 24 Jan 2024 02:03:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0B5746B007D; Wed, 24 Jan 2024 02:03:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EBEE26B007E; Wed, 24 Jan 2024 02:03:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D617F6B0075 for ; Wed, 24 Jan 2024 02:03:28 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7C1C11C0F7E for ; Wed, 24 Jan 2024 07:03:28 +0000 (UTC) X-FDA: 81713313696.18.C379D5B Received: from out-185.mta0.migadu.com (out-185.mta0.migadu.com [91.218.175.185]) by imf25.hostedemail.com (Postfix) with ESMTP id 741D7A0014 for ; Wed, 24 Jan 2024 07:03:26 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ccXBI1cM; spf=pass (imf25.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.185 as permitted sender) smtp.mailfrom=muchun.song@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1706079806; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=1HVP16o1VtXDA7W9OZNwq3dT+EsNFJe/EB2vPP8VZRM=; b=6Tt/jOJmmsERxeC40lTBxESGGBKC8kQZLMswYu2St8h5d7RyWVW79eg60YHi1uKnm96MSc ehlP4PxmYMiM2bTKzk1IDYTzL/TQM9bBYkyiqi/HqKRHSbQRYvfucdOLlGJPyFaxtcSTBG Sw/Lz/h8YYlNNa3bH9WRmU3qMJlJxUA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706079806; a=rsa-sha256; cv=none; b=TBoKXeUlicJ+VEDVPoutI4YcOwT5FlnPyaIG+DfX2dtLrFqebTK1Lm3eogEu0Pr7MXtO5r /SJUw5n2dVMb73Ehn1qWxuiDf3AA9FFFOZd/OpgTLoM5ONjgXsXsP0+kro+rJfLrHaO7nb FIvcuByPoHrUiSeTzFZzlec+anHNP5M= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=ccXBI1cM; spf=pass (imf25.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.185 as permitted sender) smtp.mailfrom=muchun.song@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1706079804; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1HVP16o1VtXDA7W9OZNwq3dT+EsNFJe/EB2vPP8VZRM=; b=ccXBI1cM3RgoCTV66lUC3XI2f9ilnUOAyO5eHsoD2RskZr6BZipluQmDZutMDOzM9Tl9YL 3E8DjOCDvljN0mPiMgBErH1linpiUX9Ch3B3Ggij+N+IrJ0eFTGsXM4juNPCV8FKfEiyta I+l098X1/g44btaBFjEnItvBkxNl6BY= Date: Wed, 24 Jan 2024 15:03:15 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v3] Hugetlb pages should not be reserved by shmat() if SHM_NORESERVE To: Prakash Sangappa , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: mike.kravetz@oracle.com, akpm@linux-foundation.org References: <1706040282-12388-1-git-send-email-prakash.sangappa@oracle.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: <1706040282-12388-1-git-send-email-prakash.sangappa@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 741D7A0014 X-Rspam-User: X-Stat-Signature: edzdfu57a8r4g8qfwks85ubno9zimnpg X-Rspamd-Server: rspam03 X-HE-Tag: 1706079806-990598 X-HE-Meta: U2FsdGVkX1+AfngJr0Q0I73cqHaYY8gXvW1g6Uu89FAmgitQhFZWh59uuy7pHbvVgTRbp18eNaSYneeYEpai4djEFMCVhMGnNl7RXHGXOJLt/VHytEuT1fJYnfNMU9OlTI5sYgu8FylmAKFkaBm6yMb2PGUYMBumwIkuz+aJukNpdYoNx6y8SKZb4ygRVYUCdAt0/LS1GAL3a1dqDH4pZXvvIZ8qSQb9PDiva92a3rAgXI0YHPC1j6kBzL72cPY6HeqHryYSGEtBQJNisapbUCPkdTLkpSjKo//WrryrZflQYnkfcbqc/7eJnk0SYzXU61aJZbu8fo6Z3oBRNxMYsj1xDAbs/7+MZM9LBUdBokJYEugUjJefsl2byC+mJoAyelwM++ehDR4jcc54TGVgPBKstjrqI/PinZwkZR8cALTbj8Eo3O8aOqZxHqxoqqCFVu1jGdzRQaC+8JsAkRyYXeQlqJQfFKF2T8vFdBKVfsJSn0aRbAUoDelFDwvWU2k7YqGr3eWcRRywzIXa0gEltT0BiMNSjLCPxfJ8nqHBQ66pSl/eHnP4maJZJa4/1jixPGUfjakeAaaUVGXfHAtxQMmkOVeOZqvHxtMG4EZopMdQ6AUyELIVt/5/htIfMq0H2Ho10WhLT4Leavnthqp7gjBAEC7JCVmIgt2K7Y3kiFH/q9ucpNu1rTp6JRPNcQhgsruorZb85ES/nmFg2LKNcD4mtO5kttH49L1i6iTAMdmEEs4FAc5TFrHp3Oso6G7xiDk/dFVXNNNDV+d5nuQXSm830oKqqNXcNxlhjxhR6S3tpA7tLVIX/WhgS6avuc4OYY0zXCx0YkErksxjHpGKpqRn/AAnPSr40grv+q1DNrD2kHeyYmw/FGB/rX3I+hCWUA35CmhdzKdkv0eqdU8r9j71BWCOu3XEvsJGHNf2EYSlvS5J3b1/5jciqBJEqO2RG5EW7hxjAq/pxKWpMve cFVe1j3l RbZuUIcrnDeNtGROMWmnozUHnWhyQwFiQ9KxMyL5xLRdWvTKLDobydgO2WSqW+HUpMihZY9Nv8s9Rtk19ozL37kNkqjdr63+Stye3FSJ3cH/SC7aDGrkQM3GiIdym01/JAZewzw2kem0mpZrPzgC80WBENRKROGHDdC4H X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/1/24 04:04, Prakash Sangappa wrote: > For shared memory of type SHM_HUGETLB, hugetlb pages are reserved in > shmget() call. If SHM_NORESERVE flags is specified then the hugetlb > pages are not reserved. However when the shared memory is attached > with the shmat() call the hugetlb pages are getting reserved incorrectly > for SHM_HUGETLB shared memory created with SHM_NORESERVE which is a bug. > > ------------------------------- > Following test shows the issue. > > $cat shmhtb.c > > int main() > { > int shmflags = 0660 | IPC_CREAT | SHM_HUGETLB | SHM_NORESERVE; > int shmid; > > shmid = shmget(SKEY, SHMSZ, shmflags); > if (shmid < 0) > { > printf("shmat: shmget() failed, %d\n", errno); > return 1; > } > printf("After shmget()\n"); > system("cat /proc/meminfo | grep -i hugepages_"); > > shmat(shmid, NULL, 0); > printf("\nAfter shmat()\n"); > system("cat /proc/meminfo | grep -i hugepages_"); > > shmctl(shmid, IPC_RMID, NULL); > return 0; > } > > #sysctl -w vm.nr_hugepages=20 > #./shmhtb > > After shmget() > HugePages_Total: 20 > HugePages_Free: 20 > HugePages_Rsvd: 0 > HugePages_Surp: 0 > > After shmat() > HugePages_Total: 20 > HugePages_Free: 20 > HugePages_Rsvd: 5 <-- > HugePages_Surp: 0 > -------------------------------- > > Fix is to ensure that hugetlb pages are not reserved for SHM_HUGETLB shared > memory in the shmat() call. > Signed-off-by: Prakash Sangappa BTW, it is better to add a Fixes tag to specify which commit that this commit aims to fix. Acked-by: Muchun Song Thanks.