Commit-ID: af2cf278ef4f9289f88504c3e03cb12f76027575 Gitweb: http://git.kernel.org/tip/af2cf278ef4f9289f88504c3e03cb12f76027575 Author: Ingo Molnar <[email protected]> AuthorDate: Thu, 14 Jul 2016 13:22:49 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 15 Jul 2016 10:26:24 +0200
x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() So when memory hotplug removes a piece of physical memory from pagetable mappings, it also frees the underlying PGD entry. This complicates PGD management, so don't do this. We can keep the PGD mapped and the PUD table all clear - it's only a single 4K page per 512 GB of memory hotplugged. Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Andy Lutomirski <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Waiman Long <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/064ff6c7275734537f969e876f6cd0baa954d2cc.1468527351.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/mm/init_64.c | 27 --------------------------- 1 file changed, 27 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index bb88fbc..e14f870 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -702,27 +702,6 @@ static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud) spin_unlock(&init_mm.page_table_lock); } -/* Return true if pgd is changed, otherwise return false. */ -static bool __meminit free_pud_table(pud_t *pud_start, pgd_t *pgd) -{ - pud_t *pud; - int i; - - for (i = 0; i < PTRS_PER_PUD; i++) { - pud = pud_start + i; - if (!pud_none(*pud)) - return false; - } - - /* free a pud table */ - free_pagetable(pgd_page(*pgd), 0); - spin_lock(&init_mm.page_table_lock); - pgd_clear(pgd); - spin_unlock(&init_mm.page_table_lock); - - return true; -} - static void __meminit remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end, bool direct) @@ -913,7 +892,6 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct) unsigned long addr; pgd_t *pgd; pud_t *pud; - bool pgd_changed = false; for (addr = start; addr < end; addr = next) { next = pgd_addr_end(addr, end); @@ -924,13 +902,8 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct) pud = (pud_t *)pgd_page_vaddr(*pgd); remove_pud_table(pud, addr, next, direct); - if (free_pud_table(pud, pgd)) - pgd_changed = true; } - if (pgd_changed) - sync_global_pgds(start, end - 1, 1); - flush_tlb_all(); }
