Messages in this thread Patch in this message | | | Date | Fri, 14 Feb 2003 06:06:16 -0500 (EST) | From | Zwane Mwaikambo <> | Subject | [PATCH][2.5] flush_tlb_all is not preempt safe. |
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Hi, Considering that smp_call_function isn't allowed to hold a lock reference and within smp_call_function we lock and unlock call_lock thus triggering a preempt point. Therefore we can't guarantee that we'll be on the same processor when we hit do_flush_tlb_all_local.
void flush_tlb_all(void) { preempt_disable(); smp_call_function (flush_tlb_all_ipi,0,1,1);
do_flush_tlb_all_local(); preempt_enable(); }
...
smp_call_function() { spin_lock(call_lock); ... spin_unlock(call_lock); <preemption point> }
...
do_flush_tlb_all_local() - possibly not executing on same processor anymore.
This case is fixed in my smp_call_function_on_cpu patches by not allowing smp_call_function to invoke preemption.
Index: linux-2.5.60-uml/arch/i386/kernel/smp.c =================================================================== RCS file: /build/cvsroot/linux-2.5.60/arch/i386/kernel/smp.c,v retrieving revision 1.1.1.1 diff -u -r1.1.1.1 smp.c --- linux-2.5.60-uml/arch/i386/kernel/smp.c 10 Feb 2003 22:14:16 -0000 1.1.1.1 +++ linux-2.5.60-uml/arch/i386/kernel/smp.c 14 Feb 2003 10:59:19 -0000 @@ -452,9 +452,11 @@ void flush_tlb_all(void) { + preempt_disable(); smp_call_function (flush_tlb_all_ipi,0,1,1); do_flush_tlb_all_local(); + preempt_enable(); } /* -- function.linuxpower.ca - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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