The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ac790d09885d36143076e7e02825c541e8eee899 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" aneesh.kumar@linux.ibm.com Date: Wed, 29 Jun 2022 10:39:25 +0530 Subject: [PATCH] powerpc/memhotplug: Add add_pages override for PPC

With commit ffa0b64e3be5 ("powerpc: Fix virt_addr_valid() for 64-bit Book3E & 32-bit") the kernel now validate the addr against high_memory value. This results in the below BUG_ON with dax pfns.

[ 635.798741][T26531] kernel BUG at mm/page_alloc.c:5521! 1:mon> e cpu 0x1: Vector: 700 (Program Check) at [c000000007287630] pc: c00000000055ed48: free_pages.part.0+0x48/0x110 lr: c00000000053ca70: tlb_finish_mmu+0x80/0xd0 sp: c0000000072878d0 msr: 800000000282b033 current = 0xc00000000afabe00 paca = 0xc00000037ffff300 irqmask: 0x03 irq_happened: 0x05 pid = 26531, comm = 50-landscape-sy kernel BUG at :5521! Linux version 5.19.0-rc3-14659-g4ec05be7c2e1 (kvaneesh@ltc-boston8) (gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #625 SMP Thu Jun 23 00:35:43 CDT 2022 1:mon> t [link register ] c00000000053ca70 tlb_finish_mmu+0x80/0xd0 [c0000000072878d0] c00000000053ca54 tlb_finish_mmu+0x64/0xd0 (unreliable) [c000000007287900] c000000000539424 exit_mmap+0xe4/0x2a0 [c0000000072879e0] c00000000019fc1c mmput+0xcc/0x210 [c000000007287a20] c000000000629230 begin_new_exec+0x5e0/0xf40 [c000000007287ae0] c00000000070b3cc load_elf_binary+0x3ac/0x1e00 [c000000007287c10] c000000000627af0 bprm_execve+0x3b0/0xaf0 [c000000007287cd0] c000000000628414 do_execveat_common.isra.0+0x1e4/0x310 [c000000007287d80] c00000000062858c sys_execve+0x4c/0x60 [c000000007287db0] c00000000002c1b0 system_call_exception+0x160/0x2c0 [c000000007287e10] c00000000000c53c system_call_common+0xec/0x250

The fix is to make sure we update high_memory on memory hotplug. This is similar to what x86 does in commit 3072e413e305 ("mm/memory_hotplug: introduce add_pages")

Fixes: ffa0b64e3be5 ("powerpc: Fix virt_addr_valid() for 64-bit Book3E & 32-bit") Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220629050925.31447-1-aneesh.kumar@linux.ibm.com

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index c2ce2e60c8f0..7aa12e88c580 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -358,6 +358,10 @@ config ARCH_SUSPEND_NONZERO_CPU def_bool y depends on PPC_POWERNV || PPC_PSERIES

+config ARCH_HAS_ADD_PAGES + def_bool y + depends on ARCH_ENABLE_MEMORY_HOTPLUG + config PPC_DCR_NATIVE bool

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 52b77684acda..a97128a48817 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -105,6 +105,37 @@ void __ref arch_remove_linear_mapping(u64 start, u64 size) vm_unmap_aliases(); }

+/* + * After memory hotplug the variables max_pfn, max_low_pfn and high_memory need + * updating. + */ +static void update_end_of_memory_vars(u64 start, u64 size) +{ + unsigned long end_pfn = PFN_UP(start + size); + + if (end_pfn > max_pfn) { + max_pfn = end_pfn; + max_low_pfn = end_pfn; + high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1; + } +} + +int __ref add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages, + struct mhp_params *params) +{ + int ret; + + ret = __add_pages(nid, start_pfn, nr_pages, params); + if (ret) + return ret; + + /* update max_pfn, max_low_pfn and high_memory */ + update_end_of_memory_vars(start_pfn << PAGE_SHIFT, + nr_pages << PAGE_SHIFT); + + return ret; +} + int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { @@ -115,7 +146,7 @@ int __ref arch_add_memory(int nid, u64 start, u64 size, rc = arch_create_linear_mapping(nid, start, size, params); if (rc) return rc; - rc = __add_pages(nid, start_pfn, nr_pages, params); + rc = add_pages(nid, start_pfn, nr_pages, params); if (rc) arch_remove_linear_mapping(start, size); return rc;