Re: [PATCH] fix oops on resume from apm bios initiated suspend

[mikpe@csd.uu.se]

Pavel Machek writes:
 > Hi!
 > 
 > > Didn't know if you caught this one, but it fixes it for me and others
 > > who responded on the list.  
 > > 
 > > mm is NULL for kernel threads without their own context.  active_mm is
 > > maintained the one we lazly switch from.
 > > 
 > > Without this patch, apm bios initiated suspend events (eg panel close) 
 > > cause an oops on resume in the LDT restore, killing kapmd, which causes
 > > further events to not be polled.
 > 
 > Ouch, okay, this looks good. Andrew please apply.
 > 
 > [I guess this is trivial enough for trivial patch monkey if andrew
 > does not want to take it...]
 > 								Pavel
 > 
 > > ===== arch/i386/kernel/suspend.c 1.16 vs edited =====
 > > --- 1.16/arch/i386/kernel/suspend.c	Sat May 17 16:09:37 2003
 > > +++ edited/arch/i386/kernel/suspend.c	Sat May 24 05:00:02 2003
 > > @@ -114,7 +114,7 @@
 > >          cpu_gdt_table[cpu][GDT_ENTRY_TSS].b &= 0xfffffdff;
 > >  
 > >  	load_TR_desc();				/* This does ltr */
 > > -	load_LDT(&current->mm->context);	/* This does lldt */
 > > +	load_LDT(&current->active_mm->context);	/* This does lldt */

No one has still explained WHY kapmd's current->mm is NULL for some people,
while it obviously is non-NULL for many others. That worries me a lot more.