On Tue, 03 Nov, at 09:07:34AM, Ingo Molnar wrote: > > Unfortunately this commit is now part of the v4.3 kernel, so we need a quick > solution or a quick revert.
Quick solution: --- >From ebb589d9cd83cce838d540aea1951d9b902eb0bc Mon Sep 17 00:00:00 2001 From: Matt Fleming <[email protected]> Date: Tue, 3 Nov 2015 13:40:41 +0000 Subject: [PATCH] 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). Reported-by: Ying Huang <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Laszlo Ersek <[email protected]> Cc: <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Andy Lutomirski <[email protected]> Signed-off-by: Matt Fleming <[email protected]> --- 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 a3cccbfc5f77..2b8cbd693da8 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(); -- 2.6.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
