diff options
| author | Jérôme Glisse | 2017-06-24 14:05:14 -0400 |
|---|---|---|
| committer | Ingo Molnar | 2017-06-26 11:44:19 +0200 |
| commit | 98fe3633c5a44e5ee3d642907739eb0210407886 (patch) | |
| tree | 3408d8dfefe07787adc5bb32946b2a0ae22167e2 | |
| parent | c0bc126f97fb929b3ae02c1c62322645d70eb408 (diff) | |
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>
| -rw-r--r-- | arch/x86/mm/init_64.c | 8 |
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) |