From: David Hildenbrand Date: Wed, 11 Nov 2020 14:53:18 +0000 (+0100) Subject: powerpc/mm: protect linear mapping modifications by a mutex X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e5b2af044f31bf18defa557a8cd11c23caefa34c;p=linux.git powerpc/mm: protect linear mapping modifications by a mutex 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. Signed-off-by: David Hildenbrand Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201111145322.15793-5-david@redhat.com --- diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 8a86d81f8df02..ca5c4b54c366c 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