4.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dave Jiang <[email protected]> commit c6ee7a548e2c291398b4f32c1f741c66b9f98e1c upstream. The numa_emulation() routine in the 'uniform' case walks through all the physical 'memblk' instances and divides them into N emulated nodes with split_nodes_size_interleave_uniform(). As each physical node is consumed it is removed from the physical memblk array in the numa_remove_memblk_from() helper. Since split_nodes_size_interleave_uniform() handles advancing the array as the 'memblk' is consumed it is expected that the base of the array is always specified as the argument. Otherwise, on multi-socket (> 2) configurations the uniform-split capability can generate an invalid numa configuration leading to boot failures with signatures like the following: rcu: INFO: rcu_sched detected stalls on CPUs/tasks: Sending NMI from CPU 0 to CPUs 2: NMI backtrace for cpu 2 CPU: 2 PID: 1332 Comm: pgdatinit0 Not tainted 4.19.0-rc8-next-20181019-baseline #59 RIP: 0010:__init_single_page.isra.74+0x81/0x90 [..] Call Trace: deferred_init_pages+0xaa/0xe3 deferred_init_memmap+0x18f/0x318 kthread+0xf8/0x130 ? deferred_free_pages.isra.105+0xc9/0xc9 ? kthread_stop+0x110/0x110 ret_from_fork+0x35/0x40 Fixes: 1f6a2c6d9f121 ("x86/numa_emulation: Introduce uniform split capability") Signed-off-by: Dave Jiang <[email protected]> Signed-off-by: Dan Williams <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Alexander Duyck <[email protected]> Reviewed-by: Dave Hansen <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/154049911459.2685845.9210186007479774286.st...@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/mm/numa_emulation.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/arch/x86/mm/numa_emulation.c +++ b/arch/x86/mm/numa_emulation.c @@ -400,9 +400,17 @@ void __init numa_emulation(struct numa_m n = simple_strtoul(emu_cmdline, &emu_cmdline, 0); ret = -1; for_each_node_mask(i, physnode_mask) { + /* + * The reason we pass in blk[0] is due to + * numa_remove_memblk_from() called by + * emu_setup_memblk() will delete entry 0 + * and then move everything else up in the pi.blk + * array. Therefore we should always be looking + * at blk[0]. + */ ret = split_nodes_size_interleave_uniform(&ei, &pi, - pi.blk[i].start, pi.blk[i].end, 0, - n, &pi.blk[i], nid); + pi.blk[0].start, pi.blk[0].end, 0, + n, &pi.blk[0], nid); if (ret < 0) break; if (ret < n) {
