From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-422771-1518026278-2-3673187585369293038 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no ("Email failed DMARC policy for domain") X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, RCVD_IN_DNSWL_MED -2.3, SPF_PASS -0.001, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='140.211.166.136', Host='smtp3.osuosl.org', Country='US', FromHeader='com', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-IgnoreVacation: yes ("Email failed DMARC policy for domain") X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: driverdev-devel-bounces@linuxdriverproject.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518026277; b=LTLuxyx4JDR88W2FzhmCkL3Ew4O0SomAm4IcpkH5CblGsa9 fD91jmY3GD3ebz9ReUYlCgJiBqt3Nz8KSbCWype8EMdBCVEYLKAa9WpmMpe3QTi4 ZNslmmc0CC/4Onu0RJKRhshJKDZUlhyl2SKKl37SU7qBX3XRgzdhG1pRZVSZnUcJ 9GzR2ogYlI9SHrzAPFOqSKFsPiI3v/ret8gS58fDmK2gmpPV5lFoXe6UzJMbd/BT Ag3MlHy3WVSiG2lB5jLUiXMoI1vSS5gdBSkgI1XxIebtxFyA90Yzc+SwDjlfxvoy rRr6+tDkR2en+4AnBTMs5mo6K1bS856MsE7j6XQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:subject:date:message-id :in-reply-to:references:list-id:list-unsubscribe:list-archive :list-post:list-help:list-subscribe:cc:mime-version:content-type :content-transfer-encoding:sender; s=arctest; t=1518026277; bh=v IsRHWwxGxC10imzdkUxvfSHdKkkJBvfxUMJG6Ioa5k=; b=s4hSdQYijYvMOoWKy uIMJjj1O7loHSM2u7jtlJ4+cwZ56kgOZuH1Xf+V03e8F99EzcM+lSzDaI48GuLp7 IjbWAUB0coZxx7FiXYWXtrjr6qVyJb1ktbuF2Fkly377tVk7VABO81IIPP/r5xHZ 2p4JWmcxuGrO/+QfL5UhhzyM4w9XhuFm0wB4rupYkKwfysNRoTELz8Eue4jI/PpS 0a2Z/hkUM/viA4Og3rMgkAChoaTbhAO1lY5NVA+8NFWMGzGX/J1qIlt9uUGRCoRh Rp5xkVp+qYHInc/DjwifRbzVfuL15DVJ4vyjH11wlh1dM1QwNZESuUa1nZ3SLWg3 /hlwA== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=140.211.166.136 (smtp3.osuosl.org); spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org smtp.helo=silver.osuosl.org; x-aligned-from=fail; x-ptr=fail x-ptr-helo=silver.osuosl.org x-ptr-lookup=smtp3.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=redhat.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128 Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=140.211.166.136 (smtp3.osuosl.org); spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org smtp.helo=silver.osuosl.org; x-aligned-from=fail; x-ptr=fail x-ptr-helo=silver.osuosl.org x-ptr-lookup=smtp3.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=redhat.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128 X-Remote-Delivered-To: driverdev-devel@osuosl.org From: Vitaly Kuznetsov To: devel@linuxdriverproject.org Subject: [PATCH RESEND 3/4] hv_balloon: fix bugs in num_pages_onlined accounting Date: Wed, 7 Feb 2018 18:50:02 +0100 Message-Id: <20180207175003.28859-4-vkuznets@redhat.com> In-Reply-To: <20180207175003.28859-1-vkuznets@redhat.com> References: <20180207175003.28859-1-vkuznets@redhat.com> X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.24 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Otubo , Stephen Hemminger , Haiyang Zhang , Alex Ng , linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Our num_pages_onlined accounting is buggy: 1) In case we're offlining a memory block which was present at boot (e.g. when there was no hotplug at all) we subtract 32k from 0 and as num_pages_onlined is unsigned get a very big positive number. 2) Commit 6df8d9aaf3af ("Drivers: hv: balloon: Correctly update onlined page count") made num_pages_onlined counter accurate on onlining but totally incorrect on offlining for partly populated regions: no matter how many pages were onlined and what was actually added to num_pages_onlined counter we always subtract the full region (32k) so again, num_pages_onlined can wrap around zero. By onlining/offlining the same partly populated region multiple times we can make the situation worse. Solve these issues by doing accurate accounting on offlining: walk HAS list, check for covered range and gaps. Fixes: 6df8d9aaf3af ("Drivers: hv: balloon: Correctly update onlined page count") Signed-off-by: Vitaly Kuznetsov --- drivers/hv/hv_balloon.c | 82 +++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 69 insertions(+), 13 deletions(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index 5b8e1ad1bcfe..7514a32d0de4 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -576,11 +576,65 @@ static struct hv_dynmem_device dm_device; static void post_status(struct hv_dynmem_device *dm); #ifdef CONFIG_MEMORY_HOTPLUG +static inline bool has_pfn_is_backed(struct hv_hotadd_state *has, + unsigned long pfn) +{ + struct hv_hotadd_gap *gap; + + /* The page is not backed. */ + if ((pfn < has->covered_start_pfn) || (pfn >= has->covered_end_pfn)) + return false; + + /* Check for gaps. */ + list_for_each_entry(gap, &has->gap_list, list) { + if ((pfn >= gap->start_pfn) && (pfn < gap->end_pfn)) + return false; + } + + return true; +} + +static unsigned long hv_page_offline_check(unsigned long start_pfn, + unsigned long nr_pages) +{ + unsigned long pfn = start_pfn, count = 0; + struct hv_hotadd_state *has; + bool found; + + while (pfn < start_pfn + nr_pages) { + /* + * Search for HAS which covers the pfn and when we find one + * count how many consequitive PFNs are covered. + */ + found = false; + list_for_each_entry(has, &dm_device.ha_region_list, list) { + while ((pfn >= has->start_pfn) && + (pfn < has->end_pfn) && + (pfn < start_pfn + nr_pages)) { + found = true; + if (has_pfn_is_backed(has, pfn)) + count++; + pfn++; + } + } + + /* + * This PFN is not in any HAS (e.g. we're offlining a region + * which was present at boot), no need to account for it. Go + * to the next one. + */ + if (!found) + pfn++; + } + + return count; +} + static int hv_memory_notifier(struct notifier_block *nb, unsigned long val, void *v) { struct memory_notify *mem = (struct memory_notify *)v; - unsigned long flags; + unsigned long flags, pfn_count; switch (val) { case MEM_ONLINE: @@ -593,7 +647,19 @@ static int hv_memory_notifier(struct notifier_block *nb, unsigned long val, case MEM_OFFLINE: spin_lock_irqsave(&dm_device.ha_lock, flags); - dm_device.num_pages_onlined -= mem->nr_pages; + pfn_count = hv_page_offline_check(mem->start_pfn, + mem->nr_pages); + if (pfn_count <= dm_device.num_pages_onlined) { + dm_device.num_pages_onlined -= pfn_count; + } else { + /* + * We're offlining more pages than we managed to online. + * This is unexpected. In any case don't let + * num_pages_onlined wrap around zero. + */ + WARN_ON_ONCE(1); + dm_device.num_pages_onlined = 0; + } spin_unlock_irqrestore(&dm_device.ha_lock, flags); break; case MEM_GOING_ONLINE: @@ -612,19 +678,9 @@ static struct notifier_block hv_memory_nb = { /* Check if the particular page is backed and can be onlined and online it. */ static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg) { - struct hv_hotadd_gap *gap; - unsigned long pfn = page_to_pfn(pg); - - /* The page is not backed. */ - if ((pfn < has->covered_start_pfn) || (pfn >= has->covered_end_pfn)) + if (!has_pfn_is_backed(has, page_to_pfn(pg))) return; - /* Check for gaps. */ - list_for_each_entry(gap, &has->gap_list, list) { - if ((pfn >= gap->start_pfn) && (pfn < gap->end_pfn)) - return; - } - /* This frame is currently backed; online the page. */ __online_page_set_limits(pg); __online_page_increment_counters(pg); -- 2.14.3 _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel