4.16-stable review patch. If anyone has any objections, please let me know.
------------------ From: Balbir Singh <[email protected]> commit fb5924fddf9ee31db04da7ad4e8c3434a387101b upstream. This patch adds support for flushing potentially dirty cache lines when memory is hot-plugged/hot-un-plugged. The support is currently limited to 64 bit systems. The bug was exposed when mappings for a device were actually hot-unplugged and plugged in back later. A similar issue was observed during the development of memtrace, but memtrace does it's own flushing of region via a custom routine. These patches do a flush both on hotplug/unplug to clear any stale data in the cache w.r.t mappings, there is a small race window where a clean cache line may be created again just prior to tearing down the mapping. The patches were tested by disabling the flush routines in memtrace and doing I/O on the trace file. The system immediately checkstops (quite reliablly if prior to the hot-unplug of the memtrace region, we memset the regions we are about to hot unplug). After these patches no custom flushing is needed in the memtrace code. Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: [email protected] # v4.14+ Signed-off-by: Balbir Singh <[email protected]> Acked-by: Reza Arbab <[email protected]> Reviewed-by: Rashmica Gupta <[email protected]> Signed-off-by: Michael Ellerman <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/powerpc/mm/mem.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -143,6 +143,7 @@ int arch_add_memory(int nid, u64 start, start, start + size, rc); return -EFAULT; } + flush_inval_dcache_range(start, start + size); return __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock); } @@ -169,6 +170,7 @@ int arch_remove_memory(u64 start, u64 si /* Remove htab bolted mappings for this section of memory */ start = (unsigned long)__va(start); + flush_inval_dcache_range(start, start + size); ret = remove_section_mapping(start, start + size); /* Ensure all vmalloc mappings are flushed in case they also
