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x86/numa_emulation: Fix uniform-split numa emulation
authorDave Jiang <dave.jiang@intel.com>
Thu, 25 Oct 2018 20:26:45 +0000 (13:26 -0700)
committerThomas Gleixner <tglx@linutronix.de>
Tue, 30 Oct 2018 10:36:43 +0000 (11:36 +0100)
commitc6ee7a548e2c291398b4f32c1f741c66b9f98e1c
treebcf612b752b9b93ca3f98388bcc60b776004b8b1
parent7847c7be0481558f17e3ef3b03f573677fd30d29
x86/numa_emulation: Fix uniform-split numa emulation

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 <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/154049911459.2685845.9210186007479774286.stgit@dwillia2-desk3.amr.corp.intel.com
arch/x86/mm/numa_emulation.c