Commit-ID: 1c5dac914794f0170e1582d8ffdee52d30e0e4dd Gitweb: http://git.kernel.org/tip/1c5dac914794f0170e1582d8ffdee52d30e0e4dd Author: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> AuthorDate: Tue, 3 Nov 2015 13:40:41 +0000 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 4 Nov 2015 11:48:47 +0100 x86/setup: Fix recent boot crash on 32-bit SMP machines The LKP test robot reported that the bug fix in commit f5f3497cad8c ("x86/setup: Extend low identity map to cover whole kernel range") causes CONFIG_X86_32 SMP machines to crash on boot when trying to bring AP cpus online. The above commit erroneously copies too many of the PGD entries to the low memory region of 'identity_page_table', resulting in some of the kernel mappings for PAGE_OFFSET being trashed because, KERNEL_PGD_PTRS > KERNEL_PGD_BOUNDARY The maximum number of PGD entries we can copy without corrupting the kernel mapping is KERNEL_PGD_BOUNDARY or pgd_index(PAGE_OFFSET). Fixes: f5f3497cad8c "x86/setup: Extend low identity map to cover whole kernel range" Reported-by: Ying Huang <ying.huang@xxxxxxxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Laszlo Ersek <lersek@xxxxxxxxxx> Cc: lkp@xxxxxx Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20151103140354.GA2653@xxxxxxxxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- arch/x86/kernel/setup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index a3cccbf..2b8cbd6 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1180,7 +1180,7 @@ void __init setup_arch(char **cmdline_p) */ clone_pgd_range(initial_page_table, swapper_pg_dir + KERNEL_PGD_BOUNDARY, - KERNEL_PGD_PTRS); + KERNEL_PGD_BOUNDARY); #endif tboot_probe(); -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html