Hi All, this mail correct the following mistakes in last mail 1, remove test patch attached 2, format patch to satisfy rules i am so sorry for my mistake Hi Andrew, this patch is part of https://lkml.org/lkml/2016/7/26/347 and isn't merged in as you advised in another mail, i release this patch against linus's mainline for fixing relevant bugs completely >From 5d79c31d755dc3f03ecc5b4134f21793258636cd Mon Sep 17 00:00:00 2001 From: zijun_hu <zijun_hu@xxxxxxx> Date: Tue, 2 Aug 2016 12:35:28 +0800 Subject: [PATCH] mm/memblock.c: fix NULL dereference error it causes NULL dereference error and failure to get type_a->regions[0] info if parameter type_b of __next_mem_range_rev() == NULL the bugs are fixed by checking before dereferring and initializing idx_b to 0 the approach is tested by dumping all types of region via __memblock_dump_all() and __next_mem_range_rev() fixed to UART separately the result is okay after checking the logs Signed-off-by: zijun_hu <zijun_hu@xxxxxxx> Tested-by: zijun_hu <zijun_hu@xxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> --- mm/memblock.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/memblock.c b/mm/memblock.c index ff5ff3b..250dd48 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -994,7 +994,10 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags, if (*idx == (u64)ULLONG_MAX) { idx_a = type_a->cnt - 1; - idx_b = type_b->cnt; + if (type_b != NULL) + idx_b = type_b->cnt; + else + idx_b = 0; } for (; idx_a >= 0; idx_a--) { -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>