> Either way, random panics are not the appropriate response ;-)
>
> if it can't cope with that, why isn't it failing the request ???
There is a crappy test in swap_on(). It should check against MAX_SWAPFILES
and not do this conversion back and forth. Some architectures may not
check if we are beyond the boundaries of what a swap entry can take.
Why is this strange this in there? Are there architectures that support
less than 32 swap devices?
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux-2.6.17-rc5-mm2/mm/swapfile.c
===================================================================
--- linux-2.6.17-rc5-mm2.orig/mm/swapfile.c 2006-06-01 10:03:07.127259731 -0700
+++ linux-2.6.17-rc5-mm2/mm/swapfile.c 2006-06-05 13:24:56.000823157 -0700
@@ -1384,6 +1384,9 @@ asmlinkage long sys_swapon(const char __
struct inode *inode = NULL;
int did_down = 0;
+ if (nr_swapfiles >= MAX_SWAPFILES)
+ return -E2BIG;
+
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
spin_lock(&swap_lock);
@@ -1392,22 +1395,6 @@ asmlinkage long sys_swapon(const char __
if (!(p->flags & SWP_USED))
break;
error = -EPERM;
- /*
- * Test if adding another swap device is possible. There are
- * two limiting factors: 1) the number of bits for the swap
- * type swp_entry_t definition and 2) the number of bits for
- * the swap type in the swap ptes as defined by the different
- * architectures. To honor both limitations a swap entry
- * with swap offset 0 and swap type ~0UL is created, encoded
- * to a swap pte, decoded to a swp_entry_t again and finally
- * the swap type part is extracted. This will mask all bits
- * from the initial ~0UL that can't be encoded in either the
- * swp_entry_t or the architecture definition of a swap pte.
- */
- if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
- spin_unlock(&swap_lock);
- goto out;
- }
if (type >= nr_swapfiles)
nr_swapfiles = type+1;
INIT_LIST_HEAD(&p->extent_list);
-
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