* [steiner@sgi.com: Re: TLB flushing in 2.4.14]
@ 2001-12-07 6:45 Benjamin LaHaise
0 siblings, 0 replies; only message in thread
From: Benjamin LaHaise @ 2001-12-07 6:45 UTC (permalink / raw
To: torvalds; +Cc: linux-mm, Jack Steiner
Hey folks,
I'm just going through my backlog, and this patch looks reasonable to
me. Linus, could you drop this into 2.5?
-ben
----- Forwarded message from Jack Steiner <steiner@sgi.com> -----
From: Jack Steiner <steiner@sgi.com>
Subject: Re: TLB flushing in 2.4.14
To: bcrl@redhat.com (Benjamin LaHaise)
Date: Wed, 28 Nov 2001 14:01:14 -0600 (CST)
In-Reply-To: <20011127132519.B19568@redhat.com> from "Benjamin LaHaise" at Nov 27, 2001 01:25:19 PM
X-Mailer: ELM [version 2.5 PL2]
>
> On Tue, Nov 27, 2001 at 12:22:28PM -0600, Jack Steiner wrote:
> > Do you see any problems with this patch??
> >
> > (I also sent a copy of this to Andrea Arcangeli)
>
> Yes. Your system will now happily corrupt memory if you run ps or top at
> the right time. I'd suggested adding an mm->dead flag and using that
> instead, but Linus is the keeper of the vm code, so run it by him.
You are right, of course. I should have studied the code better.
Here is a much cleaner fix (ignore the previous patch completely). This
keeps all the changes in just one spot - no changes to fs/exec.c.
Do you see any problems here...
--- linux_base/include/asm-generic/tlb.h Wed Oct 31 08:06:36 2001
+++ linux/include/asm-generic/tlb.h Wed Nov 28 13:56:03 2001
@@ -43,7 +43,7 @@
tlb->mm = mm;
/* Use fast mode if there is only one user of this mm (this process) */
- tlb->nr = (atomic_read(&(mm)->mm_users) == 1) ? ~0UL : 0UL;
+ tlb->nr = (atomic_read(&(mm)->mm_users) <= 1) ? ~0UL : 0UL;
return tlb;
}
@@ -70,6 +70,8 @@
/* tlb_finish_mmu
* Called at the end of the shootdown operation to free up any resources
* that were required. The page talbe lock is still held at this point.
+ * Note that no TLB flushes are needed if there are no users of the mm
+ * context.
*/
static inline void tlb_finish_mmu(struct free_pte_ctx *ctx, unsigned long start, unsigned long end)
{
@@ -77,7 +79,8 @@
/* Handle the fast case first. */
if (ctx->nr == ~0UL) {
- flush_tlb_range(ctx->mm, start, end);
+ if (ctx->mm->mmap)
+ flush_tlb_range(ctx->mm, start, end);
return;
}
nr = ctx->nr;
--
Thanks
Jack Steiner (651-683-5302) (vnet 233-5302) steiner@sgi.com
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2001-12-07 6:45 [steiner@sgi.com: Re: TLB flushing in 2.4.14] Benjamin LaHaise
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