Many thanks for the testing.

On Mon, 21 Mar 2005, David S. Miller wrote:
> 
> This adjustment of addr relative to floor is very
> strange, it can advance "addr" (and thus "start")
> past the end of the VMA we are unmapping.

Not strange, it's just trying to skip a pointless iteration.

> In fact, it is miraculious that this free_pud_range()
> calling loop terminates properly!  Actually, it is
> no mystery, since the next PGD address is the same
> for both the original and adjusted value of "addr".
> So the loop terminates after the first iteration.

Miraculous indeed, I hadn't realized those do {} while () loops
were as robust as that.  But it's certainly wrong to have been
calling them once in this case, even if they did recover.

> Anyways, there's the full analysis, what do you make
> of this Hugh? :-)

Much better than I deserve.  Silly me.  This patch should fix it.

[PATCH 6/5] freepgt: fix addr,end check

Fix placing of free_p?d_range's check for addr against end.

Signed-off-by: Hugh Dickins <[EMAIL PROTECTED]>

--- freepgt5/mm/memory.c        2005-03-22 04:28:40.000000000 +0000
+++ freepgt6/mm/memory.c        2005-03-22 05:11:05.000000000 +0000
@@ -127,11 +127,6 @@ static inline void free_pmd_range(struct
        unsigned long next;
        unsigned long start;
 
-       if (end - 1 > ceiling - 1)
-               end -= PMD_SIZE;
-       if (addr > end - 1)
-               return;
-
        start = addr;
        pmd = pmd_offset(pud, addr);
        do {
@@ -202,7 +197,9 @@ void free_pgd_range(struct mmu_gather **
                        return;
        }
        ceiling &= PMD_MASK;
-       if (addr > ceiling - 1)
+       if (end - 1 > ceiling - 1)
+               end -= PMD_SIZE;
+       if (addr > end - 1)
                return;
 
        start = addr;
-
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