From 9661d5bcd058fe15b4138a00d96bd36516134543 Mon Sep 17 00:00:00 2001 From: Yasuaki Ishimatsu Date: Fri, 22 Aug 2014 13:27:34 -0700 Subject: [PATCH] x86/mm/hotplug: Modify PGD entry when removing memory When hot-adding/removing memory, sync_global_pgds() is called for synchronizing PGD to PGD entries of all processes MM. But when hot-removing memory, sync_global_pgds() does not work correctly. At first, sync_global_pgds() checks whether target PGD is none or not. And if PGD is none, the PGD is skipped. But when hot-removing memory, PGD may be none since PGD may be cleared by free_pud_table(). So when sync_global_pgds() is called after hot-removing memory, sync_global_pgds() should not skip PGD even if the PGD is none. And sync_global_pgds() must clear PGD entries of all processes MM. Currently sync_global_pgds() does not clear PGD entries of all processes MM when hot-removing memory. So when hot adding memory which is same memory range as removed memory after hot-removing memory, following call traces are shown: kernel BUG at arch/x86/mm/init_64.c:206! ... [] kernel_physical_mapping_init+0x1b2/0x1d2 [] init_memory_mapping+0x1d4/0x380 [] arch_add_memory+0x3d/0xd0 [] add_memory+0xb9/0x1b0 [] acpi_memory_device_add+0x1af/0x28e [] acpi_bus_device_attach+0x8c/0xf0 [] acpi_ns_walk_namespace+0xc8/0x17f [] ? acpi_bus_type_and_status+0xb7/0xb7 [] ? acpi_bus_type_and_status+0xb7/0xb7 [] acpi_walk_namespace+0x95/0xc5 [] acpi_bus_scan+0x9a/0xc2 [] acpi_scan_bus_device_check+0x8b/0x12e [] acpi_scan_device_check+0x13/0x15 [] acpi_os_execute_deferred+0x25/0x32 [] process_one_work+0x17b/0x460 [] worker_thread+0x11b/0x400 [] ? rescuer_thread+0x400/0x400 [] kthread+0xcf/0xe0 [] ? kthread_create_on_node+0x140/0x140 [] ret_from_fork+0x7c/0xb0 [] ? kthread_create_on_node+0x140/0x140 This patch clears PGD entries of all processes MM when sync_global_pgds() is called after hot-removing memory Signed-off-by: Yasuaki Ishimatsu Acked-by: Toshi Kani Signed-off-by: Andrew Morton Cc: Tang Chen Cc: Gu Zheng Cc: Zhang Yanfei Cc: Linus Torvalds Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pgtable_64.h | 3 ++- arch/x86/mm/fault.c | 2 +- arch/x86/mm/init_64.c | 27 +++++++++++++++++++-------- 3 files changed, 22 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h index 5be9063545d2..809abb335627 100644 --- a/arch/x86/include/asm/pgtable_64.h +++ b/arch/x86/include/asm/pgtable_64.h @@ -115,7 +115,8 @@ static inline void native_pgd_clear(pgd_t *pgd) native_set_pgd(pgd, native_make_pgd(0)); } -extern void sync_global_pgds(unsigned long start, unsigned long end); +extern void sync_global_pgds(unsigned long start, unsigned long end, + int removed); /* * Conversion functions: convert a page and protection to a page entry, diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index a24194681513..d393ac669cc0 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -350,7 +350,7 @@ out: void vmalloc_sync_all(void) { - sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END); + sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END, 0); } /* diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 0e996c0a7eff..529625118ff6 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -178,7 +178,7 @@ __setup("noexec32=", nonx32_setup); * When memory was added/removed make sure all the processes MM have * suitable PGD entries in the local PGD level page. */ -void sync_global_pgds(unsigned long start, unsigned long end) +void sync_global_pgds(unsigned long start, unsigned long end, int removed) { unsigned long address; @@ -186,7 +186,12 @@ void sync_global_pgds(unsigned long start, unsigned long end) const pgd_t *pgd_ref = pgd_offset_k(address); struct page *page; - if (pgd_none(*pgd_ref)) + /* + * When it is called after memory hot remove, pgd_none() + * returns true. In this case (removed == 1), we must clear + * the PGD entries in the local PGD level page. + */ + if (pgd_none(*pgd_ref) && !removed) continue; spin_lock(&pgd_lock); @@ -199,12 +204,18 @@ void sync_global_pgds(unsigned long start, unsigned long end) pgt_lock = &pgd_page_get_mm(page)->page_table_lock; spin_lock(pgt_lock); - if (pgd_none(*pgd)) - set_pgd(pgd, *pgd_ref); - else + if (!pgd_none(*pgd_ref) && !pgd_none(*pgd)) BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + if (removed) { + if (pgd_none(*pgd_ref) && !pgd_none(*pgd)) + pgd_clear(pgd); + } else { + if (pgd_none(*pgd)) + set_pgd(pgd, *pgd_ref); + } + spin_unlock(pgt_lock); } spin_unlock(&pgd_lock); @@ -633,7 +644,7 @@ kernel_physical_mapping_init(unsigned long start, } if (pgd_changed) - sync_global_pgds(addr, end - 1); + sync_global_pgds(addr, end - 1, 0); __flush_tlb_all(); @@ -995,7 +1006,7 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct) } if (pgd_changed) - sync_global_pgds(start, end - 1); + sync_global_pgds(start, end - 1, 1); flush_tlb_all(); } @@ -1342,7 +1353,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) else err = vmemmap_populate_basepages(start, end, node); if (!err) - sync_global_pgds(start, end - 1); + sync_global_pgds(start, end - 1, 0); return err; } -- 2.39.5