The patch titled Subject: memblock: make for_each_mem_range() traverse MEMBLOCK_HOTPLUG regions has been added to the -mm tree. Its filename is memblock-make-for_each_mem_range-traverse-memblock_hotplug-regions.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/memblock-make-for_each_mem_range-t... and later at https://ozlabs.org/~akpm/mmotm/broken-out/memblock-make-for_each_mem_range-t...

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------------------------------------------------------ From: Mike Rapoport rppt@linux.ibm.com Subject: memblock: make for_each_mem_range() traverse MEMBLOCK_HOTPLUG regions

Commit b10d6bca8720 ("arch, drivers: replace for_each_membock() with for_each_mem_range()") didn't take into account that when there is movable_node parameter in the kernel command line, for_each_mem_range() would skip ranges marked with MEMBLOCK_HOTPLUG.

The page table setup code in POWER uses for_each_mem_range() to create the linear mapping of the physical memory and since the regions marked as MEMORY_HOTPLUG are skipped, they never make it to the linear map.

A later access to the memory in those ranges will fail:

[ 2.271743] BUG: Unable to handle kernel data access on write at 0xc000000400000000 [ 2.271984] Faulting instruction address: 0xc00000000008a3c0 [ 2.272568] Oops: Kernel access of bad area, sig: 11 [#1] [ 2.272683] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries [ 2.273063] Modules linked in: [ 2.273435] CPU: 0 PID: 53 Comm: kworker/u2:0 Not tainted 5.13.0 #7 [ 2.273832] NIP: c00000000008a3c0 LR: c0000000003c1ed8 CTR: 0000000000000040 [ 2.273918] REGS: c000000008a57770 TRAP: 0300 Not tainted (5.13.0) [ 2.274036] MSR: 8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 84222202 XER: 20040000 [ 2.274454] CFAR: c0000000003c1ed4 DAR: c000000400000000 DSISR: 42000000 IRQMASK: 0 [ 2.274454] GPR00: c0000000003c1ed8 c000000008a57a10 c0000000019da700 c000000400000000 [ 2.274454] GPR04: 0000000000000280 0000000000000180 0000000000000400 0000000000000200 [ 2.274454] GPR08: 0000000000000100 0000000000000080 0000000000000040 0000000000000300 [ 2.274454] GPR12: 0000000000000380 c000000001bc0000 c0000000001660c8 c000000006337e00 [ 2.274454] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 2.274454] GPR20: 0000000040000000 0000000020000000 c000000001a81990 c000000008c30000 [ 2.274454] GPR24: c000000008c20000 c000000001a81998 000fffffffff0000 c000000001a819a0 [ 2.274454] GPR28: c000000001a81908 c00c000001000000 c000000008c40000 c000000008a64680 [ 2.275520] NIP [c00000000008a3c0] clear_user_page+0x50/0x80 [ 2.276333] LR [c0000000003c1ed8] __handle_mm_fault+0xc88/0x1910 [ 2.276688] Call Trace: [ 2.276839] [c000000008a57a10] [c0000000003c1e94] __handle_mm_fault+0xc44/0x1910 (unreliable) [ 2.277142] [c000000008a57af0] [c0000000003c2c90] handle_mm_fault+0x130/0x2a0 [ 2.277331] [c000000008a57b40] [c0000000003b5f08] __get_user_pages+0x248/0x610 [ 2.277541] [c000000008a57c40] [c0000000003b848c] __get_user_pages_remote+0x12c/0x3e0 [ 2.277768] [c000000008a57cd0] [c000000000473f24] get_arg_page+0x54/0xf0 [ 2.277959] [c000000008a57d10] [c000000000474a7c] copy_string_kernel+0x11c/0x210 [ 2.278159] [c000000008a57d80] [c00000000047663c] kernel_execve+0x16c/0x220 [ 2.278361] [c000000008a57dd0] [c000000000166270] call_usermodehelper_exec_async+0x1b0/0x2f0 [ 2.278543] [c000000008a57e10] [c00000000000d5ec] ret_from_kernel_thread+0x5c/0x70 [ 2.278870] Instruction dump: [ 2.279214] 79280fa4 79271764 79261f24 794ae8e2 7ca94214 7d683a14 7c893a14 7d893050 [ 2.279416] 7d4903a6 60000000 60000000 60000000 <7c001fec> 7c091fec 7c081fec 7c051fec [ 2.280193] ---[ end trace 490b8c67e6075e09 ]---

Making for_each_mem_range() include MEMBLOCK_HOTPLUG regions in the traversal fixes this issue.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1976100 Link: https://lkml.kernel.org/r/20210712071132.20902-1-rppt@kernel.org Fixes: b10d6bca8720 ("arch, drivers: replace for_each_membock() with for_each_mem_range()") Signed-off-by: Mike Rapoport rppt@linux.ibm.com Tested-by: Greg Kurz groug@kaod.org Reviewed-by: David Hildenbrand david@redhat.com Cc: stable@vger.kernel.org [5.10+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

include/linux/memblock.h | 4 ++-- mm/memblock.c | 3 ++- 2 files changed, 4 insertions(+), 3 deletions(-)

--- a/include/linux/memblock.h~memblock-make-for_each_mem_range-traverse-memblock_hotplug-regions +++ a/include/linux/memblock.h @@ -209,7 +209,7 @@ static inline void __next_physmem_range( */ #define for_each_mem_range(i, p_start, p_end) \ __for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE, \ - MEMBLOCK_NONE, p_start, p_end, NULL) + MEMBLOCK_HOTPLUG, p_start, p_end, NULL)

/** * for_each_mem_range_rev - reverse iterate through memblock areas from @@ -220,7 +220,7 @@ static inline void __next_physmem_range( */ #define for_each_mem_range_rev(i, p_start, p_end) \ __for_each_mem_range_rev(i, &memblock.memory, NULL, NUMA_NO_NODE, \ - MEMBLOCK_NONE, p_start, p_end, NULL) + MEMBLOCK_HOTPLUG, p_start, p_end, NULL)

/** * for_each_reserved_mem_range - iterate over all reserved memblock areas --- a/mm/memblock.c~memblock-make-for_each_mem_range-traverse-memblock_hotplug-regions +++ a/mm/memblock.c @@ -947,7 +947,8 @@ static bool should_skip_region(struct me return true;

/* skip hotpluggable memory regions if needed */ - if (movable_node_is_enabled() && memblock_is_hotpluggable(m)) + if (movable_node_is_enabled() && memblock_is_hotpluggable(m) && + !(flags & MEMBLOCK_HOTPLUG)) return true;

/* if we want mirror memory skip non-mirror memory regions */ _

Patches currently in -mm which might be from rppt@linux.ibm.com are

memblock-make-for_each_mem_range-traverse-memblock_hotplug-regions.patch mm-page_alloc-always-initialize-memory-map-for-the-holes.patch microblaze-simplify-pte_alloc_one_kernel.patch mm-introduce-memmap_alloc-to-unify-memory-map-allocation.patch memblock-stop-poisoning-raw-allocations.patch mm-remove-pfn_valid_within-and-config_holes_in_zone.patch mm-memory_hotplug-cleanup-after-removal-of-pfn_valid_within.patch