From 1dbf527c51c6c20c19869c8125cb5b87c3d09506 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 2 May 2007 19:27:12 +0200 Subject: [PATCH] i386: Make COMPAT_VDSO runtime selectable. Now that relocation of the VDSO for COMPAT_VDSO users is done at runtime rather than compile time, it is possible to enable/disable compat mode at runtime. This patch allows you to enable COMPAT_VDSO mode with "vdso=2" on the kernel command line, or via sysctl. (Switching on a running system shouldn't be done lightly; any process which was relying on the compat VDSO will be upset if it goes away.) The COMPAT_VDSO config option still exists, but if enabled it just makes vdso_enabled default to VDSO_COMPAT. +From: Hugh Dickins Fix oops from i386-make-compat_vdso-runtime-selectable.patch. Even mingetty at system startup finds it easy to trigger an oops while reading /proc/PID/maps: though it has a good hold on the mm itself, that cannot stop exit_mm() from resetting tsk->mm to NULL. (It is usually show_map()'s call to get_gate_vma() which oopses, and I expect we could change that to check priv->tail_vma instead; but no matter, even m_start()'s call just after get_task_mm() is racy.) Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Zachary Amsden Cc: "Jan Beulich" Cc: Eric W. Biederman Cc: Andi Kleen Cc: Ingo Molnar Cc: Roland McGrath --- Documentation/kernel-parameters.txt | 1 + 1 file changed, 1 insertion(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 84c3bd05c63..4287696f18d 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1820,6 +1820,7 @@ and is between 256 and 4096 characters. It is defined in the file [USBHID] The interval which mice are to be polled at. vdso= [IA-32,SH] + vdso=2: enable compat VDSO (default with COMPAT_VDSO) vdso=1: enable VDSO (default) vdso=0: disable VDSO mapping -- cgit v1.2.3