From patchwork Wed Nov 11 14:53:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11897989 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5D575921 for ; Wed, 11 Nov 2020 14:53:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 08169206D9 for ; Wed, 11 Nov 2020 14:53:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RvWF4jXb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 08169206D9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E19CE6B0081; 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bh=B8t8a4IKn/4UDggl6V593VlD1u/4N3i8dDQlBOovljE=; b=RvWF4jXbL1uuoHYNfWd0cfvoHntiLtuB9LtDNM9W/89Ahzn6RrjvR3cClXqUkLbyawk+sf pM2ODIFNPLNPjMXaR4Z7sb+zR866k/3mKJdp30fXQcnOJzTMRYzvHB7M5O+QxbeYiS66Z+ rfl65iqcTrlcE/1PZlwx61MmaQUAl5A= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-379-RyV7I3fYPbC0bpz0uPuaqA-1; Wed, 11 Nov 2020 09:53:35 -0500 X-MC-Unique: RyV7I3fYPbC0bpz0uPuaqA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8AB7618CB735; Wed, 11 Nov 2020 14:53:33 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9FAFE389; Wed, 11 Nov 2020 14:53:30 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Michael Ellerman , stable@vger.kernel.org, Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta , Andrew Morton , Mike Rapoport , Michal Hocko , Oscar Salvador , Wei Yang Subject: [PATCH v2 1/8] powernv/memtrace: don't leak kernel memory to user space Date: Wed, 11 Nov 2020 15:53:15 +0100 Message-Id: <20201111145322.15793-2-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: We currently leak kernel memory to user space, because memory offlining doesn't do any implicit clearing of memory and we are missing explicit clearing of memory. Let's keep it simple and clear pages before removing the linear mapping. Reproduced in QEMU/TCG with 10 GiB of main memory: [root@localhost ~]# dd obs=9G if=/dev/urandom of=/dev/null [... wait until "free -m" used counter no longer changes and cancel] 19665802+0 records in 1+0 records out 9663676416 bytes (9.7 GB, 9.0 GiB) copied, 135.548 s, 71.3 MB/s [root@localhost ~]# cat /sys/devices/system/memory/block_size_bytes 40000000 [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 402.978663][ T1086] page:000000001bc4bc74 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x24900 [ 402.980063][ T1086] flags: 0x7ffff000001000(reserved) [ 402.980415][ T1086] raw: 007ffff000001000 c00c000000924008 c00c000000924008 0000000000000000 [ 402.980627][ T1086] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 [ 402.980845][ T1086] page dumped because: unmovable page [ 402.989608][ T1086] Offlined Pages 16384 [ 403.324155][ T1086] memtrace: Allocated trace memory on node 0 at 0x0000000200000000 Before this patch: [root@localhost ~]# hexdump -C /sys/kernel/debug/powerpc/memtrace/00000000/trace | head 00000000 c8 25 72 51 4d 26 36 c5 5c c2 56 15 d5 1a cd 10 |.%rQM&6.\.V.....| 00000010 19 b9 50 b2 cb e3 60 b8 ec 0a f3 ec 4b 3c 39 f0 |..P...`.....K<9.|$ 00000020 4e 5a 4c cf bd 26 19 ff 37 79 13 67 24 b7 b8 57 |NZL..&..7y.g$..W|$ 00000030 98 3e f5 be 6f 14 6a bd a4 52 bc 6e e9 e0 c1 5d |.>..o.j..R.n...]|$ 00000040 76 b3 ae b5 88 d7 da e3 64 23 85 2c 10 88 07 b6 |v.......d#.,....|$ 00000050 9a d8 91 de f7 50 27 69 2e 64 9c 6f d3 19 45 79 |.....P'i.d.o..Ey|$ 00000060 6a 6f 8a 61 71 19 1f c7 f1 df 28 26 ca 0f 84 55 |jo.aq.....(&...U|$ 00000070 01 3f be e4 e2 e1 da ff 7b 8c 8e 32 37 b4 24 53 |.?......{..27.$S|$ 00000080 1b 70 30 45 56 e6 8c c4 0e b5 4c fb 9f dd 88 06 |.p0EV.....L.....|$ 00000090 ef c4 18 79 f1 60 b1 5c 79 59 4d f4 36 d7 4a 5c |...y.`.\yYM.6.J\|$ After this patch: [root@localhost ~]# hexdump -C /sys/kernel/debug/powerpc/memtrace/00000000/trace | head 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 40000000 Reported-by: Michael Ellerman Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: stable@vger.kernel.org # v4.14+ Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador --- arch/powerpc/platforms/powernv/memtrace.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c index 6828108486f8..eea1f94482ff 100644 --- a/arch/powerpc/platforms/powernv/memtrace.c +++ b/arch/powerpc/platforms/powernv/memtrace.c @@ -67,6 +67,23 @@ static int change_memblock_state(struct memory_block *mem, void *arg) return 0; } +static void memtrace_clear_range(unsigned long start_pfn, + unsigned long nr_pages) +{ + unsigned long pfn; + + /* + * As pages are offline, we cannot trust the memmap anymore. As HIGHMEM + * does not apply, avoid passing around "struct page" and use + * clear_page() instead directly. + */ + for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) { + if (IS_ALIGNED(pfn, PAGES_PER_SECTION)) + cond_resched(); + clear_page(__va(PFN_PHYS(pfn))); + } +} + /* called with device_hotplug_lock held */ static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages) { @@ -111,6 +128,11 @@ static u64 memtrace_alloc_node(u32 nid, u64 size) lock_device_hotplug(); for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) { if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) { + /* + * Clear the range while we still have a linear + * mapping. + */ + memtrace_clear_range(base_pfn, nr_pages); /* * Remove memory in memory block size chunks so that * iomem resources are always split to the same size and From patchwork Wed Nov 11 14:53:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11897991 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2AE3C921 for ; 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Wed, 11 Nov 2020 14:53:35 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id D95D1380; Wed, 11 Nov 2020 14:53:33 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , stable@vger.kernel.org, Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta Subject: [PATCH v2 2/8] powernv/memtrace: fix crashing the kernel when enabling concurrently Date: Wed, 11 Nov 2020 15:53:16 +0100 Message-Id: <20201111145322.15793-3-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: It's very easy to crash the kernel right now by simply trying to enable memtrace concurrently, hammering on the "enable" interface loop.sh: #!/bin/bash dmesg --console-off while true; do echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable done [root@localhost ~]# loop.sh & [root@localhost ~]# loop.sh & Resulting quickly in a kernel crash. Let's properly protect using a mutex. Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: stable@vger.kernel.org# v4.14+ Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador --- arch/powerpc/platforms/powernv/memtrace.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c index eea1f94482ff..0e42fe2d7b6a 100644 --- a/arch/powerpc/platforms/powernv/memtrace.c +++ b/arch/powerpc/platforms/powernv/memtrace.c @@ -30,6 +30,7 @@ struct memtrace_entry { char name[16]; }; +static DEFINE_MUTEX(memtrace_mutex); static u64 memtrace_size; static struct memtrace_entry *memtrace_array; @@ -279,6 +280,7 @@ static int memtrace_online(void) static int memtrace_enable_set(void *data, u64 val) { + int rc = -EAGAIN; u64 bytes; /* @@ -291,25 +293,31 @@ static int memtrace_enable_set(void *data, u64 val) return -EINVAL; } + mutex_lock(&memtrace_mutex); + /* Re-add/online previously removed/offlined memory */ if (memtrace_size) { if (memtrace_online()) - return -EAGAIN; + goto out_unlock; } - if (!val) - return 0; + if (!val) { + rc = 0; + goto out_unlock; + } /* Offline and remove memory */ if (memtrace_init_regions_runtime(val)) - return -EINVAL; + goto out_unlock; if (memtrace_init_debugfs()) - return -EINVAL; + goto out_unlock; memtrace_size = val; - - return 0; + rc = 0; +out_unlock: + mutex_unlock(&memtrace_mutex); + return rc; } static int memtrace_enable_get(void *data, u64 *val) From patchwork Wed Nov 11 14:53:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11897993 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 86D82921 for ; Wed, 11 Nov 2020 14:53:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 35E482068D for ; 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Wed, 11 Nov 2020 14:53:38 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 45E3727BB5; Wed, 11 Nov 2020 14:53:35 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta , Andrew Morton , Mike Rapoport , Michal Hocko , Oscar Salvador , Wei Yang Subject: [PATCH v2 3/8] powerpc/mm: factor out creating/removing linear mapping Date: Wed, 11 Nov 2020 15:53:17 +0100 Message-Id: <20201111145322.15793-4-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: We want to stop abusing memory hotplug infrastructure in memtrace code to perform allocations and remove the linear mapping. Instead we will use alloc_contig_pages() and remove the linear mapping manually. Let's factor out creating/removing the linear mapping into arch_create_linear_mapping() / arch_remove_linear_mapping() - so in the future, we might be able to have whole arch_add_memory() / arch_remove_memory() be implemented in common code. Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador --- arch/powerpc/mm/mem.c | 41 +++++++++++++++++++++++----------- include/linux/memory_hotplug.h | 3 +++ 2 files changed, 31 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 01ec2a252f09..8a86d81f8df0 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -120,34 +120,26 @@ static void flush_dcache_range_chunked(unsigned long start, unsigned long stop, } } -int __ref arch_add_memory(int nid, u64 start, u64 size, - struct mhp_params *params) +int __ref arch_create_linear_mapping(int nid, u64 start, u64 size, + struct mhp_params *params) { - unsigned long start_pfn = start >> PAGE_SHIFT; - unsigned long nr_pages = size >> PAGE_SHIFT; int rc; start = (unsigned long)__va(start); rc = create_section_mapping(start, start + size, nid, params->pgprot); if (rc) { - pr_warn("Unable to create mapping for hot added memory 0x%llx..0x%llx: %d\n", + pr_warn("Unable to create linear mapping for 0x%llx..0x%llx: %d\n", start, start + size, rc); return -EFAULT; } - - return __add_pages(nid, start_pfn, nr_pages, params); + return 0; } -void __ref arch_remove_memory(int nid, u64 start, u64 size, - struct vmem_altmap *altmap) +void __ref arch_remove_linear_mapping(u64 start, u64 size) { - unsigned long start_pfn = start >> PAGE_SHIFT; - unsigned long nr_pages = size >> PAGE_SHIFT; int ret; - __remove_pages(start_pfn, nr_pages, altmap); - /* Remove htab bolted mappings for this section of memory */ start = (unsigned long)__va(start); flush_dcache_range_chunked(start, start + size, FLUSH_CHUNK_SIZE); @@ -160,6 +152,29 @@ void __ref arch_remove_memory(int nid, u64 start, u64 size, */ vm_unmap_aliases(); } + +int __ref arch_add_memory(int nid, u64 start, u64 size, + struct mhp_params *params) +{ + unsigned long start_pfn = start >> PAGE_SHIFT; + unsigned long nr_pages = size >> PAGE_SHIFT; + int rc; + + rc = arch_create_linear_mapping(nid, start, size, params); + if (rc) + return rc; + return __add_pages(nid, start_pfn, nr_pages, params); +} + +void __ref arch_remove_memory(int nid, u64 start, u64 size, + struct vmem_altmap *altmap) +{ + unsigned long start_pfn = start >> PAGE_SHIFT; + unsigned long nr_pages = size >> PAGE_SHIFT; + + __remove_pages(start_pfn, nr_pages, altmap); + arch_remove_linear_mapping(start, size); +} #endif #ifndef CONFIG_NEED_MULTIPLE_NODES diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index d65c6fdc5cfc..00b9e9bd3850 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -375,6 +375,9 @@ extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum); extern struct zone *zone_for_pfn_range(int online_type, int nid, unsigned start_pfn, unsigned long nr_pages); +extern int arch_create_linear_mapping(int nid, u64 start, u64 size, + struct mhp_params *params); +void arch_remove_linear_mapping(u64 start, u64 size); #endif /* CONFIG_MEMORY_HOTPLUG */ #endif /* __LINUX_MEMORY_HOTPLUG_H */ From patchwork Wed Nov 11 14:53:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11897995 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6C755921 for ; Wed, 11 Nov 2020 14:53:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1CFC02068D for ; Wed, 11 Nov 2020 14:53:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="P8ERmhKv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CFC02068D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; 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bh=GSQatxuwdd1ehWeHPVVOm8FQ78oIMefwI0KM3vx9OUY=; b=P8ERmhKvywP9zkOAMk/7usCy0iof0zlG0EVBS6o8TH4DuqoiWvluj7MfFcdK2laohK2KKV O6n/miktCrecp95Mx8fPnRCAmfLzN3R7ARISiQmbU0Sk43/6eqGx3A95FmaG252lF+fxwg YTF1m9WVn64imVjmHJETlTdK0nhAKfA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-310-eMn4ZS-3NWCR9QdUC20pPQ-1; Wed, 11 Nov 2020 09:53:43 -0500 X-MC-Unique: eMn4ZS-3NWCR9QdUC20pPQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D269A8049CC; Wed, 11 Nov 2020 14:53:41 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3A9F9380; Wed, 11 Nov 2020 14:53:39 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta , Andrew Morton , Mike Rapoport , Michal Hocko , Oscar Salvador , Wei Yang Subject: [PATCH v2 4/8] powerpc/mm: protect linear mapping modifications by a mutex Date: Wed, 11 Nov 2020 15:53:18 +0100 Message-Id: <20201111145322.15793-5-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: This code currently relies on mem_hotplug_begin()/mem_hotplug_done() - create_section_mapping()/remove_section_mapping() implementations cannot tollerate getting called concurrently. Let's prepare for callers (memtrace) not holding any such locks (and don't force them to mess with memory hotplug locks). Other parts in these functions don't seem to rely on external locking. Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Signed-off-by: David Hildenbrand --- arch/powerpc/mm/mem.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 8a86d81f8df0..ca5c4b54c366 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -58,6 +58,7 @@ #define CPU_FTR_NOEXECUTE 0 #endif +static DEFINE_MUTEX(linear_mapping_mutex); unsigned long long memory_limit; bool init_mem_is_free; @@ -126,8 +127,10 @@ int __ref arch_create_linear_mapping(int nid, u64 start, u64 size, int rc; start = (unsigned long)__va(start); + mutex_lock(&linear_mapping_mutex); rc = create_section_mapping(start, start + size, nid, params->pgprot); + mutex_unlock(&linear_mapping_mutex); if (rc) { pr_warn("Unable to create linear mapping for 0x%llx..0x%llx: %d\n", start, start + size, rc); @@ -144,7 +147,9 @@ void __ref arch_remove_linear_mapping(u64 start, u64 size) start = (unsigned long)__va(start); flush_dcache_range_chunked(start, start + size, FLUSH_CHUNK_SIZE); + mutex_lock(&linear_mapping_mutex); ret = remove_section_mapping(start, start + size); + mutex_unlock(&linear_mapping_mutex); WARN_ON_ONCE(ret); /* Ensure all vmalloc mappings are flushed in case they also From patchwork Wed Nov 11 14:53:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11898003 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 05365921 for ; Wed, 11 Nov 2020 14:54:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 99DCE2068D for ; Wed, 11 Nov 2020 14:54:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JC5qn6dW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 99DCE2068D Authentication-Results: mail.kernel.org; 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Reviewed-by: Oscar Salvador Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Signed-off-by: David Hildenbrand --- arch/powerpc/mm/mem.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index ca5c4b54c366..c5755b9efb64 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -150,7 +150,9 @@ void __ref arch_remove_linear_mapping(u64 start, u64 size) mutex_lock(&linear_mapping_mutex); ret = remove_section_mapping(start, start + size); mutex_unlock(&linear_mapping_mutex); - WARN_ON_ONCE(ret); + if (ret) + pr_warn("Unable to remove linear mapping for 0x%llx..0x%llx: %d\n", + start, start + size, ret); /* Ensure all vmalloc mappings are flushed in case they also * hit that section of memory From patchwork Wed Nov 11 14:53:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11897997 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DA346921 for ; 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Wed, 11 Nov 2020 14:53:51 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 27E18380; Wed, 11 Nov 2020 14:53:44 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Oscar Salvador , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta , Andrew Morton , Mike Rapoport , Michal Hocko , Wei Yang , "Aneesh Kumar K.V" , Nicholas Piggin Subject: [PATCH v2 6/8] powerepc/book3s64/hash: drop WARN_ON in hash__remove_section_mapping Date: Wed, 11 Nov 2020 15:53:20 +0100 Message-Id: <20201111145322.15793-7-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: The single caller (arch_remove_linear_mapping()) prints a proper warning when this function fails. No need to eventually crash the kernel - let's drop this WARN_ON. Suggested-by: Oscar Salvador Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Cc: "Aneesh Kumar K.V" Cc: Nicholas Piggin Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador --- arch/powerpc/mm/book3s64/hash_utils.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 24702c0a92e0..d2dcb7757c68 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -845,7 +845,6 @@ int hash__remove_section_mapping(unsigned long start, unsigned long end) { int rc = htab_remove_mapping(start, end, mmu_linear_psize, mmu_kernel_ssize); - WARN_ON(rc < 0); if (resize_hpt_for_hotplug(memblock_phys_mem_size()) == -ENOSPC) pr_warn("Hash collision while resizing HPT\n"); From patchwork Wed Nov 11 14:53:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11897999 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F14F1921 for ; 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Wed, 11 Nov 2020 14:53:54 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 80D58380; Wed, 11 Nov 2020 14:53:51 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta , Andrew Morton , Mike Rapoport , Michal Hocko , Oscar Salvador , Wei Yang Subject: [PATCH v2 7/8] powerpc/mm: remove linear mapping if __add_pages() fails in arch_add_memory() Date: Wed, 11 Nov 2020 15:53:21 +0100 Message-Id: <20201111145322.15793-8-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: Let's revert what we did in case seomthing goes wrong and we return an error - as already done on arm64 and s390x. Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador --- arch/powerpc/mm/mem.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index c5755b9efb64..8b946ec68d1b 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -170,7 +170,10 @@ int __ref arch_add_memory(int nid, u64 start, u64 size, rc = arch_create_linear_mapping(nid, start, size, params); if (rc) return rc; - return __add_pages(nid, start_pfn, nr_pages, params); + rc = __add_pages(nid, start_pfn, nr_pages, params); + if (rc) + arch_remove_linear_mapping(start, size); + return rc; } void __ref arch_remove_memory(int nid, u64 start, u64 size, From patchwork Wed Nov 11 14:53:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11898001 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 52761139F for ; 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Wed, 11 Nov 2020 14:53:57 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 711F927BB5; Wed, 11 Nov 2020 14:53:54 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Michal Hocko , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Rashmica Gupta , Andrew Morton , Mike Rapoport , Michal Hocko , Oscar Salvador , Wei Yang Subject: [PATCH v2 8/8] powernv/memtrace: don't abuse memory hot(un)plug infrastructure for memory allocations Date: Wed, 11 Nov 2020 15:53:22 +0100 Message-Id: <20201111145322.15793-9-david@redhat.com> In-Reply-To: <20201111145322.15793-1-david@redhat.com> References: <20201111145322.15793-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: Let's use alloc_contig_pages() for allocating memory and remove the linear mapping manually via arch_remove_linear_mapping(). Mark all pages PG_offline, such that they will definitely not get touched - e.g., when hibernating. When freeing memory, try to revert what we did. The original idea was discussed in: https://lkml.kernel.org/r/48340e96-7e6b-736f-9e23-d3111b915b6e@redhat.com This is similar to CONFIG_DEBUG_PAGEALLOC handling on other architectures, whereby only single pages are unmapped from the linear mapping. Let's mimic what memory hot(un)plug would do with the linear mapping. We now need MEMORY_HOTPLUG and CONTIG_ALLOC as dependencies. Add a TODO that we want to use __GFP_ZERO for clearing once alloc_contig_pages() understands that. Tested with in QEMU/TCG with 10 GiB of main memory: [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 105.903043][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 145.042493][ T1080] radix-mmu: Mapped 0x0000000080000000-0x00000000c0000000 with 64.0 KiB pages [ 145.049019][ T1080] memtrace: Freed trace memory back on node 0 [ 145.333960][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 [root@localhost ~]# echo 0x80000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 213.606916][ T1080] radix-mmu: Mapped 0x0000000080000000-0x00000000c0000000 with 64.0 KiB pages [ 213.613855][ T1080] memtrace: Freed trace memory back on node 0 [ 214.185094][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 [root@localhost ~]# echo 0x100000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 234.874872][ T1080] radix-mmu: Mapped 0x0000000080000000-0x0000000100000000 with 64.0 KiB pages [ 234.886974][ T1080] memtrace: Freed trace memory back on node 0 [ 234.890153][ T1080] memtrace: Failed to allocate trace memory on node 0 [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 259.490196][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 I also made sure allocated memory is properly zeroed. Note 1: We currently won't be allocating from ZONE_MOVABLE - because our pages are not movable. However, as we don't run with any memory hot(un)plug mechanism around, we could make an exception to increase the chance of allocations succeeding. Note 2: PG_reserved isn't sufficient. E.g., kernel_page_present() used along PG_reserved in hibernation code will always return "true" on powerpc, resulting in the pages getting touched. It's too generic - e.g., indicates boot allocations. Note 3: For now, we keep using memory_block_size_bytes() as minimum granularity. Suggested-by: Michal Hocko Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Rashmica Gupta Cc: Andrew Morton Cc: Mike Rapoport Cc: Michal Hocko Cc: Oscar Salvador Cc: Wei Yang Signed-off-by: David Hildenbrand Reviewed-by: Oscar Salvador --- arch/powerpc/platforms/powernv/Kconfig | 8 +- arch/powerpc/platforms/powernv/memtrace.c | 163 ++++++++-------------- 2 files changed, 62 insertions(+), 109 deletions(-) diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig index 938803eab0ad..619b093a0657 100644 --- a/arch/powerpc/platforms/powernv/Kconfig +++ b/arch/powerpc/platforms/powernv/Kconfig @@ -27,11 +27,11 @@ config OPAL_PRD recovery diagnostics on OpenPower machines config PPC_MEMTRACE - bool "Enable removal of RAM from kernel mappings for tracing" - depends on PPC_POWERNV && MEMORY_HOTREMOVE + bool "Enable runtime allocation of RAM for tracing" + depends on PPC_POWERNV && MEMORY_HOTPLUG && CONTIG_ALLOC help - Enabling this option allows for the removal of memory (RAM) - from the kernel mappings to be used for hardware tracing. + Enabling this option allows for runtime allocation of memory (RAM) + for hardware tracing. config PPC_VAS bool "IBM Virtual Accelerator Switchboard (VAS)" diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c index 0e42fe2d7b6a..5fc9408bb0b3 100644 --- a/arch/powerpc/platforms/powernv/memtrace.c +++ b/arch/powerpc/platforms/powernv/memtrace.c @@ -51,33 +51,12 @@ static const struct file_operations memtrace_fops = { .open = simple_open, }; -static int check_memblock_online(struct memory_block *mem, void *arg) -{ - if (mem->state != MEM_ONLINE) - return -1; - - return 0; -} - -static int change_memblock_state(struct memory_block *mem, void *arg) -{ - unsigned long state = (unsigned long)arg; - - mem->state = state; - - return 0; -} - static void memtrace_clear_range(unsigned long start_pfn, unsigned long nr_pages) { unsigned long pfn; - /* - * As pages are offline, we cannot trust the memmap anymore. As HIGHMEM - * does not apply, avoid passing around "struct page" and use - * clear_page() instead directly. - */ + /* As HIGHMEM does not apply, use clear_page() directly. */ for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) { if (IS_ALIGNED(pfn, PAGES_PER_SECTION)) cond_resched(); @@ -85,72 +64,39 @@ static void memtrace_clear_range(unsigned long start_pfn, } } -/* called with device_hotplug_lock held */ -static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages) -{ - const unsigned long start = PFN_PHYS(start_pfn); - const unsigned long size = PFN_PHYS(nr_pages); - - if (walk_memory_blocks(start, size, NULL, check_memblock_online)) - return false; - - walk_memory_blocks(start, size, (void *)MEM_GOING_OFFLINE, - change_memblock_state); - - if (offline_pages(start_pfn, nr_pages)) { - walk_memory_blocks(start, size, (void *)MEM_ONLINE, - change_memblock_state); - return false; - } - - walk_memory_blocks(start, size, (void *)MEM_OFFLINE, - change_memblock_state); - - - return true; -} - static u64 memtrace_alloc_node(u32 nid, u64 size) { - u64 start_pfn, end_pfn, nr_pages, pfn; - u64 base_pfn; - u64 bytes = memory_block_size_bytes(); + const unsigned long nr_pages = PHYS_PFN(size); + unsigned long pfn, start_pfn; + struct page *page; - if (!node_spanned_pages(nid)) + /* + * Trace memory needs to be aligned to the size, which is guaranteed + * by alloc_contig_pages(). + */ + page = alloc_contig_pages(nr_pages, GFP_KERNEL | __GFP_THISNODE | + __GFP_NOWARN, nid, NULL); + if (!page) return 0; + start_pfn = page_to_pfn(page); - start_pfn = node_start_pfn(nid); - end_pfn = node_end_pfn(nid); - nr_pages = size >> PAGE_SHIFT; - - /* Trace memory needs to be aligned to the size */ - end_pfn = round_down(end_pfn - nr_pages, nr_pages); - - lock_device_hotplug(); - for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) { - if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) { - /* - * Clear the range while we still have a linear - * mapping. - */ - memtrace_clear_range(base_pfn, nr_pages); - /* - * Remove memory in memory block size chunks so that - * iomem resources are always split to the same size and - * we never try to remove memory that spans two iomem - * resources. - */ - end_pfn = base_pfn + nr_pages; - for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) { - __remove_memory(nid, pfn << PAGE_SHIFT, bytes); - } - unlock_device_hotplug(); - return base_pfn << PAGE_SHIFT; - } - } - unlock_device_hotplug(); + /* + * Clear the range while we still have a linear mapping. + * + * TODO: use __GFP_ZERO with alloc_contig_pages() once supported. + */ + memtrace_clear_range(start_pfn, nr_pages); - return 0; + /* + * Set pages PageOffline(), to indicate that nobody (e.g., hibernation, + * dumping, ...) should be touching these pages. + */ + for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) + __SetPageOffline(pfn_to_page(pfn)); + + arch_remove_linear_mapping(PFN_PHYS(start_pfn), size); + + return PFN_PHYS(start_pfn); } static int memtrace_init_regions_runtime(u64 size) @@ -220,16 +166,30 @@ static int memtrace_init_debugfs(void) return ret; } -static int online_mem_block(struct memory_block *mem, void *arg) +static int memtrace_free(int nid, u64 start, u64 size) { - return device_online(&mem->dev); + struct mhp_params params = { .pgprot = PAGE_KERNEL }; + const unsigned long nr_pages = PHYS_PFN(size); + const unsigned long start_pfn = PHYS_PFN(start); + unsigned long pfn; + int ret; + + ret = arch_create_linear_mapping(nid, start, size, ¶ms); + if (ret) + return ret; + + for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) + __ClearPageOffline(pfn_to_page(pfn)); + + free_contig_range(start_pfn, nr_pages); + return 0; } /* - * Iterate through the chunks of memory we have removed from the kernel - * and attempt to add them back to the kernel. + * Iterate through the chunks of memory we allocated and attempt to expose + * them back to the kernel. */ -static int memtrace_online(void) +static int memtrace_free_regions(void) { int i, ret = 0; struct memtrace_entry *ent; @@ -237,7 +197,7 @@ static int memtrace_online(void) for (i = memtrace_array_nr - 1; i >= 0; i--) { ent = &memtrace_array[i]; - /* We have onlined this chunk previously */ + /* We have freed this chunk previously */ if (ent->nid == NUMA_NO_NODE) continue; @@ -247,30 +207,25 @@ static int memtrace_online(void) ent->mem = 0; } - if (add_memory(ent->nid, ent->start, ent->size, MHP_NONE)) { - pr_err("Failed to add trace memory to node %d\n", + if (memtrace_free(ent->nid, ent->start, ent->size)) { + pr_err("Failed to free trace memory on node %d\n", ent->nid); ret += 1; continue; } - lock_device_hotplug(); - walk_memory_blocks(ent->start, ent->size, NULL, - online_mem_block); - unlock_device_hotplug(); - /* - * Memory was added successfully so clean up references to it - * so on reentry we can tell that this chunk was added. + * Memory was freed successfully so clean up references to it + * so on reentry we can tell that this chunk was freed. */ debugfs_remove_recursive(ent->dir); - pr_info("Added trace memory back to node %d\n", ent->nid); + pr_info("Freed trace memory back on node %d\n", ent->nid); ent->size = ent->start = ent->nid = NUMA_NO_NODE; } if (ret) return ret; - /* If all chunks of memory were added successfully, reset globals */ + /* If all chunks of memory were freed successfully, reset globals */ kfree(memtrace_array); memtrace_array = NULL; memtrace_size = 0; @@ -295,18 +250,16 @@ static int memtrace_enable_set(void *data, u64 val) mutex_lock(&memtrace_mutex); - /* Re-add/online previously removed/offlined memory */ - if (memtrace_size) { - if (memtrace_online()) - goto out_unlock; - } + /* Free all previously allocated memory. */ + if (memtrace_size && memtrace_free_regions()) + goto out_unlock; if (!val) { rc = 0; goto out_unlock; } - /* Offline and remove memory */ + /* Allocate memory. */ if (memtrace_init_regions_runtime(val)) goto out_unlock;