On Mon, Aug 8, 2016 at 10:16 PM, Mika Penttilä <mika.pentt...@nextfour.com> wrote: > On 08/08/2016 09:40 PM, Thomas Garnier wrote: >> Default implementation expects 6 pages maximum are needed for low page >> allocations. If KASLR memory randomization is enabled, the worse case >> of e820 layout would require 12 pages (no large pages). It is due to the >> PUD level randomization and the variable e820 memory layout. >> >> This bug was found while doing extensive testing of KASLR memory >> randomization on different type of hardware. >> >> Signed-off-by: Thomas Garnier <thgar...@google.com> >> --- >> Based on next-20160805 >> --- >> arch/x86/mm/init.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c >> index 6209289..3a27e6a 100644 >> --- a/arch/x86/mm/init.c >> +++ b/arch/x86/mm/init.c >> @@ -130,6 +130,14 @@ void __init early_alloc_pgt_buf(void) >> unsigned long tables = INIT_PGT_BUF_SIZE; >> phys_addr_t base; >> >> + /* >> + * Depending on the machine e860 memory layout and the PUD alignement. >> + * We may need twice more pages when KASLR memoy randomization is >> + * enabled. >> + */ >> + if (IS_ENABLED(CONFIG_RANDOMIZE_MEMORY)) >> + tables *= 2; >> + >> base = __pa(extend_brk(tables, PAGE_SIZE)); >> >> pgt_buf_start = base >> PAGE_SHIFT; >> > > You should increase the reserve also : > RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
Yes, that's right. I will resend v2 changing INIT_PGD_BUF_SIZE. > > > --Mika >
