From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 09B2413D89B for ; Wed, 26 Jun 2024 05:08:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719378509; cv=none; b=I3FApBcPAjXTamXpEnI38hsdTgbaf+HzJeGYWlDMtCw/UX4ywrBgWCpOKZRexZZPI9WYF/2aBMsO8kqahuKrpH5Z1OilDhd+FGDUPZqmpMKFEUzkUdxioWVNWoU8vQI4Qlj/1XmtEbxwJz6VsXTPK2FIfj5a8m8XtBCBrno2DNY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719378509; c=relaxed/simple; bh=tcIp/UGK2HdcAnbgBr6MhQluLLHq7D2d16NFgsGLSeo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nGyP6Cmya4FPzBh7hg2623M2kLRdp0hzssAyjJKdGn05ujRZW0gtz+GeqvwJnZMOVzRLIkLH+DAvZN9ctV1WYxcROPex5MLp3nh/XACyKdjMxW6lo6AO37K2sbUoc+SPgpoybMqgf8YC4dcS6Gm3jd48aTCkaXq7ylju0eZZ5nc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jiaqiyan.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=tD6mwDII; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jiaqiyan.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tD6mwDII" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-1fa9a618847so24225ad.0 for ; Tue, 25 Jun 2024 22:08:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1719378506; x=1719983306; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=8y7ao8RcoBqL0KFdl8TvipShcb1ljHNHWsgFR/lOgAk=; b=tD6mwDII32F5R37XRlpACf9z4VlwpYscfjH6GhdnN1xWUiIe8KlC//CwxeVyGsr328 v6jV0vN8m5fK8FX2A7n6aqyuT09Mi5ft33l+xNHeYsIhR+Wf7yrW4KFiDN0B3ObffEHx nluxkP2NIFtBujVqQvDIPSeEXct3jpVB2C68REfWj0h4uVdedVG15Fye/NQDotNDJixA 3R0mG1hC3N9pPY3fs1+hpvesxcaLjlTLqNS+jEmznmXshf5Jom+mv149VOlfDV6mHB2M 3pCwjwTOCnRWzbYEtTiMbc9hXxcqN83EUtwa05+fYWhRbuhB4fuz/c0NUFZwKupSRyDR 7JGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719378506; x=1719983306; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8y7ao8RcoBqL0KFdl8TvipShcb1ljHNHWsgFR/lOgAk=; b=iGb+qNhf4JcbTJOsG3sXg4zSCqMuORjqEYTV8meM95OagBjTssJFi/rTFbw+PHGXF9 voMaftEpz31JJmAFJt3sEotUkskmjtJXiI1xwqEmsJKpRFVlPng1pXQ6kmAwtBWmWODW Ix+JHYiGpFIpCbVjOicaVTXP/GI+GMmUa+Ib+u6DVZhheJTZ53bRz13YkMP10Uy0KfC2 7nizNffv5fxsCGAyLGoKd9HLOhO4Z667nDAYXEPW8nK2xnPZnI4C6ZqaVBsPkc2hgcIc SOs/y9L9zq4n7B/mlFsh7v1Znc9M5rwZuQfiq0T0PxQkr3bVm3TmJDPT5QKHFJV1a9AE F9dg== X-Forwarded-Encrypted: i=1; AJvYcCXM8vtoSb1NVsAOvOOQSmz/wdWKuqz7UoKrlavnxXbjZKumZFIjUryBOxLmk8GdQ3o9sstfpD2AKUIEUZkDD29vAW6Qw4INvdCB3BFPqqat X-Gm-Message-State: AOJu0YyHE+9qN2InwCoMq/DKWLu9ylsG4UcvLZ8S0clF4PSZzJf2wMqY /yVtyUYrqhyCVHnQgh2J07MhmhH4ngpoPusAxDMhzG4kzISeb/tdUASku7twJ9euta/hzipVlRS g3fRr7lVwnw== X-Google-Smtp-Source: AGHT+IFMw6f7MOlDWfVepmO+C1PVKVXo4zQODjs53YFlJ2c1BkCfmt+eu9ZUoQDtHFkvUJpUimIn1RfCeGhwow== X-Received: from yjq3.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:272f]) (user=jiaqiyan job=sendgmr) by 2002:a17:902:eccb:b0:1f9:cc3c:9dc with SMTP id d9443c01a7336-1fa104968e4mr4123865ad.5.1719378506297; Tue, 25 Jun 2024 22:08:26 -0700 (PDT) Date: Wed, 26 Jun 2024 05:08:16 +0000 In-Reply-To: <20240626050818.2277273-1-jiaqiyan@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240626050818.2277273-1-jiaqiyan@google.com> X-Mailer: git-send-email 2.45.2.741.gdbec12cfda-goog Message-ID: <20240626050818.2277273-3-jiaqiyan@google.com> Subject: [PATCH v6 2/4] mm/memory-failure: userspace controls soft-offlining pages From: Jiaqi Yan To: nao.horiguchi@gmail.com, linmiaohe@huawei.com Cc: jane.chu@oracle.com, rdunlap@infradead.org, ioworker0@gmail.com, muchun.song@linux.dev, akpm@linux-foundation.org, shuah@kernel.org, corbet@lwn.net, osalvador@suse.de, rientjes@google.com, duenwen@google.com, fvdl@google.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Jiaqi Yan Content-Type: text/plain; charset="UTF-8" Correctable memory errors are very common on servers with large amount of memory, and are corrected by ECC. Soft offline is kernel's additional recovery handling for memory pages having (excessive) corrected memory errors. Impacted page is migrated to a healthy page if inuse; the original page is discarded for any future use. The actual policy on whether (and when) to soft offline should be maintained by userspace, especially in case of an 1G HugeTLB page. Soft-offline dissolves the HugeTLB page, either in-use or free, into chunks of 4K pages, reducing HugeTLB pool capacity by 1 hugepage. If userspace has not acknowledged such behavior, it may be surprised when later failed to mmap hugepages due to lack of hugepages. In case of a transparent hugepage, it will be split into 4K pages as well; userspace will stop enjoying the transparent performance. In addition, discarding the entire 1G HugeTLB page only because of corrected memory errors sounds very costly and kernel better not doing under the hood. But today there are at least 2 such cases doing so: 1. when GHES driver sees both GHES_SEV_CORRECTED and CPER_SEC_ERROR_THRESHOLD_EXCEEDED after parsing CPER. 2. RAS Correctable Errors Collector counts correctable errors per PFN and when the counter for a PFN reaches threshold In both cases, userspace has no control of the soft offline performed by kernel's memory failure recovery. This commit gives userspace the control of softofflining any page: kernel only soft offlines raw page / transparent hugepage / HugeTLB hugepage if userspace has agreed to. The interface to userspace is a new sysctl at /proc/sys/vm/enable_soft_offline. By default its value is set to 1 to preserve existing behavior in kernel. When set to 0, soft-offline (e.g. MADV_SOFT_OFFLINE) will fail with EOPNOTSUPP. Acked-by: Miaohe Lin Signed-off-by: Jiaqi Yan --- mm/memory-failure.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 6f5ac334efba..1559e773537f 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -68,6 +68,8 @@ static int sysctl_memory_failure_early_kill __read_mostly; static int sysctl_memory_failure_recovery __read_mostly = 1; +static int sysctl_enable_soft_offline __read_mostly = 1; + atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0); static bool hw_memory_failure __read_mostly = false; @@ -141,6 +143,15 @@ static struct ctl_table memory_failure_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, + { + .procname = "enable_soft_offline", + .data = &sysctl_enable_soft_offline, + .maxlen = sizeof(sysctl_enable_soft_offline), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + } }; /* @@ -2749,8 +2760,9 @@ static int soft_offline_in_use_page(struct page *page) * @pfn: pfn to soft-offline * @flags: flags. Same as memory_failure(). * - * Returns 0 on success - * -EOPNOTSUPP for hwpoison_filter() filtered the error event + * Returns 0 on success, + * -EOPNOTSUPP for hwpoison_filter() filtered the error event, or + * disabled by /proc/sys/vm/enable_soft_offline, * < 0 otherwise negated errno. * * Soft offline a page, by migration or invalidation, @@ -2786,6 +2798,13 @@ int soft_offline_page(unsigned long pfn, int flags) return -EIO; } + if (!sysctl_enable_soft_offline) { + pr_info_once("%#lx: disabled by /proc/sys/vm/enable_soft_offline\n", + pfn); + put_ref_page(pfn, flags); + return -EOPNOTSUPP; + } + mutex_lock(&mf_mutex); if (PageHWPoison(page)) { -- 2.45.2.741.gdbec12cfda-goog