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authorJérôme Glisse <jglisse@redhat.com>2017-06-24 20:05:14 +0200
committerIngo Molnar <mingo@kernel.org>2017-06-26 11:44:19 +0200
commit98fe3633c5a44e5ee3d642907739eb0210407886 (patch)
tree3408d8dfefe07787adc5bb32946b2a0ae22167e2 /arch/x86/mm/init_64.c
parentLinux 4.12-rc7 (diff)
downloadlinux-98fe3633c5a44e5ee3d642907739eb0210407886.tar.xz
linux-98fe3633c5a44e5ee3d642907739eb0210407886.zip
x86/mm/hotplug: Fix BUG_ON() after hot-remove by not freeing PUD
Since commit: af2cf278ef4f ("x86/mm/hotplug: Don't remove PGD entries in remove_pagetable()") we no longer free PUDs so that we do not have to synchronize all PGDs on hot-remove/vfree(). But the new 5-level page table patchset reverted that for 4-level page tables, in the following commit: f2a6a7050109: ("x86: Convert the rest of the code to support p4d_t") This patch restores the damage and disables free_pud() if we are in the 4-level page table case, thus avoiding BUG_ON() after hot-remove. Signed-off-by: Jérôme Glisse <jglisse@redhat.com> [ Clarified the changelog and the code comments. ] Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Logan Gunthorpe <logang@deltatee.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170624180514.3821-1-jglisse@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm/init_64.c')
-rw-r--r--arch/x86/mm/init_64.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 95651dc58e09..0a59daf799f8 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -990,7 +990,13 @@ remove_p4d_table(p4d_t *p4d_start, unsigned long addr, unsigned long end,
pud_base = pud_offset(p4d, 0);
remove_pud_table(pud_base, addr, next, direct);
- free_pud_table(pud_base, p4d);
+ /*
+ * For 4-level page tables we do not want to free PUDs, but in the
+ * 5-level case we should free them. This code will have to change
+ * to adapt for boot-time switching between 4 and 5 level page tables.
+ */
+ if (CONFIG_PGTABLE_LEVELS == 5)
+ free_pud_table(pud_base, p4d);
}
if (direct)