On Tue, 2019-08-20 at 09:21 -0400, Song Liu wrote:
On Aug 20, 2019, at 4:16 AM, Thomas Gleixner tglx@linutronix.de wrote:
On Tue, 20 Aug 2019, Peter Zijlstra wrote:
What that code wants to do is skip to the end of the pud, a pmd_size increase will not do that. And right below this, there's a second instance of this exact pattern.
Did I get the below right?
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index b196524759ec..32b20b3cb227 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -330,12 +330,14 @@ pti_clone_pgtable(unsigned long start, unsigned long end,
pud = pud_offset(p4d, addr); if (pud_none(*pud)) {
addr &= PUD_MASK; addr += PUD_SIZE;round_up(addr, PUD_SIZE);I guess we need "round_up(addr + PMD_SIZE, PUD_SIZE)".
What does that do if start is less than PMD_SIZE away from the next PUD_SIZE boundary?
How about: round_up(addr + 1, PUD_SIZE) ?