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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! ... [<ffffffff815e0c80>] kernel_physical_mapping_init+0x1b2/0x1d2 [<ffffffff815ced94>] init_memory_mapping+0x1d4/0x380 [<ffffffff8104aebd>] arch_add_memory+0x3d/0xd0 [<ffffffff815d03d9>] add_memory+0xb9/0x1b0 [<ffffffff81352415>] acpi_memory_device_add+0x1af/0x28e [<ffffffff81325dc4>] acpi_bus_device_attach+0x8c/0xf0 [<ffffffff813413b9>] acpi_ns_walk_namespace+0xc8/0x17f [<ffffffff81325d38>] ? acpi_bus_type_and_status+0xb7/0xb7 [<ffffffff81325d38>] ? acpi_bus_type_and_status+0xb7/0xb7 [<ffffffff813418ed>] acpi_walk_namespace+0x95/0xc5 [<ffffffff81326b4c>] acpi_bus_scan+0x9a/0xc2 [<ffffffff81326bff>] acpi_scan_bus_device_check+0x8b/0x12e [<ffffffff81326cb5>] acpi_scan_device_check+0x13/0x15 [<ffffffff81320122>] acpi_os_execute_deferred+0x25/0x32 [<ffffffff8107e02b>] process_one_work+0x17b/0x460 [<ffffffff8107edfb>] worker_thread+0x11b/0x400 [<ffffffff8107ece0>] ? rescuer_thread+0x400/0x400 [<ffffffff81085aef>] kthread+0xcf/0xe0 [<ffffffff81085a20>] ? kthread_create_on_node+0x140/0x140 [<ffffffff815fc76c>] ret_from_fork+0x7c/0xb0 [<ffffffff81085a20>] ? 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 <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Toshi Kani <toshi.kani@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Gu Zheng <guz.fnst@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -115,7 +115,8 @@ static inline void native_pgd_clear(pgd_t *pgd)
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native_set_pgd(pgd, native_make_pgd(0));
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}
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extern void sync_global_pgds(unsigned long start, unsigned long end);
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extern void sync_global_pgds(unsigned long start, unsigned long end,
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int removed);
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/*
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* Conversion functions: convert a page and protection to a page entry,
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@ -350,7 +350,7 @@ static void dump_pagetable(unsigned long address)
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void vmalloc_sync_all(void)
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{
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sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END);
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sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END, 0);
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}
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/*
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@ -178,7 +178,7 @@ __setup("noexec32=", nonx32_setup);
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* When memory was added/removed make sure all the processes MM have
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* suitable PGD entries in the local PGD level page.
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*/
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void sync_global_pgds(unsigned long start, unsigned long end)
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void sync_global_pgds(unsigned long start, unsigned long end, int removed)
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{
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unsigned long address;
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@ -186,7 +186,12 @@ void sync_global_pgds(unsigned long start, unsigned long end)
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const pgd_t *pgd_ref = pgd_offset_k(address);
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struct page *page;
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if (pgd_none(*pgd_ref))
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/*
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* When it is called after memory hot remove, pgd_none()
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* returns true. In this case (removed == 1), we must clear
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* the PGD entries in the local PGD level page.
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*/
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if (pgd_none(*pgd_ref) && !removed)
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continue;
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spin_lock(&pgd_lock);
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@ -199,12 +204,18 @@ void sync_global_pgds(unsigned long start, unsigned long end)
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pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
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spin_lock(pgt_lock);
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if (pgd_none(*pgd))
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set_pgd(pgd, *pgd_ref);
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else
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if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
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BUG_ON(pgd_page_vaddr(*pgd)
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!= pgd_page_vaddr(*pgd_ref));
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if (removed) {
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if (pgd_none(*pgd_ref) && !pgd_none(*pgd))
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pgd_clear(pgd);
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} else {
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if (pgd_none(*pgd))
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set_pgd(pgd, *pgd_ref);
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}
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spin_unlock(pgt_lock);
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}
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spin_unlock(&pgd_lock);
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@ -633,7 +644,7 @@ kernel_physical_mapping_init(unsigned long start,
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}
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if (pgd_changed)
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sync_global_pgds(addr, end - 1);
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sync_global_pgds(addr, end - 1, 0);
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__flush_tlb_all();
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@ -995,7 +1006,7 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct)
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}
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if (pgd_changed)
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sync_global_pgds(start, end - 1);
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sync_global_pgds(start, end - 1, 1);
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flush_tlb_all();
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}
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@ -1342,7 +1353,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
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else
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err = vmemmap_populate_basepages(start, end, node);
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if (!err)
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sync_global_pgds(start, end - 1);
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sync_global_pgds(start, end - 1, 0);
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return err;
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}
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