The patch titled Subject: x86,mem-hotplug: modify PGD entry when removing memory has been added to the -mm tree. Its filename is x86mem-hotplug-modify-pgd-entry-when-removing-memory.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/x86mem-hotplug-modify-pgd-entry-when-removing-memory.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/x86mem-hotplug-modify-pgd-entry-when-removing-memory.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Subject: x86,mem-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@xxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx> Cc: Toshi Kani <toshi.kani@xxxxxx> Cc: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx> Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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 -puN arch/x86/include/asm/pgtable_64.h~x86mem-hotplug-modify-pgd-entry-when-removing-memory arch/x86/include/asm/pgtable_64.h --- a/arch/x86/include/asm/pgtable_64.h~x86mem-hotplug-modify-pgd-entry-when-removing-memory +++ a/arch/x86/include/asm/pgtable_64.h @@ -115,7 +115,8 @@ static inline void native_pgd_clear(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 -puN arch/x86/mm/fault.c~x86mem-hotplug-modify-pgd-entry-when-removing-memory arch/x86/mm/fault.c --- a/arch/x86/mm/fault.c~x86mem-hotplug-modify-pgd-entry-when-removing-memory +++ a/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 -puN arch/x86/mm/init_64.c~x86mem-hotplug-modify-pgd-entry-when-removing-memory arch/x86/mm/init_64.c --- a/arch/x86/mm/init_64.c~x86mem-hotplug-modify-pgd-entry-when-removing-memory +++ a/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 star 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 star 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 lo } if (pgd_changed) - sync_global_pgds(addr, end - 1); + sync_global_pgds(addr, end - 1, 0); __flush_tlb_all(); @@ -994,7 +1005,7 @@ remove_pagetable(unsigned long start, un } if (pgd_changed) - sync_global_pgds(start, end - 1); + sync_global_pgds(start, end - 1, 1); flush_tlb_all(); } @@ -1341,7 +1352,7 @@ int __meminit vmemmap_populate(unsigned 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; } _ Patches currently in -mm which might be from isimatu.yasuaki@xxxxxxxxxxxxxx are x86mem-hotplug-pass-sync_global_pgds-a-correct-argument-in-remove_pagetable.patch x86mem-hotplug-modify-pgd-entry-when-removing-memory.patch mem-hotplug-avoid-illegal-state-prefixed-with-legal-state-when-changing-state-of-memory_block.patch mem-hotplug-introduce-mmop_offline-to-replace-the-hard-coding-1.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html