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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 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 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , Wei Yang , David Hildenbrand , linux-mm@kvack.org, Paul Mackerras , Rashmica Gupta , linuxppc-dev@lists.ozlabs.org, Andrew Morton , Mike Rapoport , Oscar Salvador Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 -- 2.26.2