From: Mike Rapoport rppt@linux.ibm.com

Since the commit ce6ee46e0f39 ("mm/page_alloc: fix memory map initialization for descending nodes") initialization of the memory map relies on availability of zone_to_nid() and zone_set_nid methods to link struct page to a node.

But in 5.10 zone_to_nid() is only defined for NUMA, but not for DISCONTIGMEM which causes crashes on m68k systems with two memory banks.

For instance on ARAnyM with both ST-RAM and FastRAM atari_defconfig build produces the following crash:

Unable to handle kernel access at virtual address (ptrval) Oops: 00000000 Modules linked in: PC: [<0005fbbc>] bpf_prog_alloc_no_stats+0x5c/0xba SR: 2200 SP: (ptrval) a2: 016daa90 d0: 0000000c d1: 00000200 d2: 00000001 d3: 00000cc0 d4: 016d1f80 d5: 00034da6 a0: 305c2800 a1: 305c2a00 Process swapper (pid: 1, task=(ptrval)) Frame format=7 eff addr=31800000 ssw=0445 faddr=31800000 wb 1 stat/addr/data: 0000 00000000 00000000 wb 2 stat/addr/data: 0000 00000000 00000000 wb 3 stat/addr/data: 00c5 31800000 00000001 push data: 00000000 00000000 00000000 00000000 Stack from 3058fec8: 00000dc0 00000000 004addc2 3058ff16 0005fc34 00000238 00000000 00000210 004addc2 3058ff16 00281ae0 00000238 00000000 00000000 004addc2 004bc7ec 004aea9e 0048b0c0 3058ff16 00460042 004ba4d2 3058ff8c 004ade6a 0000007e 0000210e 0000007e 00000002 016d1f80 00034da6 000020b4 00000000 004b4764 004bc7ec 00000000 004b4760 004bc7c0 004b4744 001e4cb2 00010001 016d1fe5 016d1ff0 004994d2 003e1589 016d1f80 00412b8c 0000007e 00000001 00000001 Call Trace: [<004addc2>] sock_init+0x0/0xaa [<0005fc34>] bpf_prog_alloc+0x1a/0x66 [<004addc2>] sock_init+0x0/0xaa [<00281ae0>] bpf_prog_create+0x2e/0x7c [<004addc2>] sock_init+0x0/0xaa [<004aea9e>] ptp_classifier_init+0x22/0x44 [<004ade6a>] sock_init+0xa8/0xaa [<0000210e>] do_one_initcall+0x5a/0x150 [<00034da6>] parse_args+0x0/0x208 [<000020b4>] do_one_initcall+0x0/0x150 [<001e4cb2>] strcpy+0x0/0x1c [<00010001>] stwotoxd+0x5/0x1c [<004994d2>] kernel_init_freeable+0x154/0x1a6 [<001e4cb2>] strcpy+0x0/0x1c [<0049951a>] kernel_init_freeable+0x19c/0x1a6 [<004addc2>] sock_init+0x0/0xaa [<00321510>] kernel_init+0x0/0xd8 [<00321518>] kernel_init+0x8/0xd8 [<00321510>] kernel_init+0x0/0xd8 [<00002890>] ret_from_kernel_thread+0xc/0x14

Code: 204b 200b 4cdf 180c 4e75 700c e0aa 3682 <2748> 001c 214b 0140 022b ffbf 0002 206b 001c 2008 0680 0000 0108 2140 0108 2140 Disabling lock debugging due to kernel taint Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

Using CONFIG_NEED_MULTIPLE_NODES rather than CONFIG_NUMA to guard definitions of zone_to_nid() and zone_set_nid() fixes the issue.

Reported-by: Mikael Pettersson mikpelinux@gmail.com Fixes: ce6ee46e0f39 ("mm/page_alloc: fix memory map initialization for descending nodes") Signed-off-by: Mike Rapoport rppt@linux.ibm.com Tested-by: Mikael Pettersson mikpelinux@gmail.com --- include/linux/mmzone.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 9d0c454d23cd..63b550403317 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -445,7 +445,7 @@ struct zone { */ long lowmem_reserve[MAX_NR_ZONES];

-#ifdef CONFIG_NUMA +#ifdef CONFIG_NEED_MULTIPLE_NODES int node; #endif struct pglist_data *zone_pgdat; @@ -896,7 +896,7 @@ static inline bool populated_zone(struct zone *zone) return zone->present_pages; }

-#ifdef CONFIG_NUMA +#ifdef CONFIG_NEED_MULTIPLE_NODES static inline int zone_to_nid(struct zone *zone) { return zone->node;