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slab: fix the type of the index on freelist index accessor
Commit a41adfa ("slab: introduce byte sized index for the freelist of a slab") changes the size of freelist index and also changes prototype of accessor function to freelist index. And there was a mistake. The mistake is that although it changes the size of freelist index correctly, it changes the size of the index of freelist index incorrectly. With patch, freelist index can be 1 byte or 2 bytes, that means that num of object on on a slab can be more than 255. So we need more than 1 byte for the index to find the index of free object on freelist. But, above patch makes this index type 1 byte, so slab which have more than 255 objects cannot work properly and in consequence of it, the system cannot boot. This issue was reported by Steven King on m68knommu which would use 2 bytes freelist index: https://lkml.org/lkml/2014/4/16/433 To fix is easy. To change the type of the index of freelist index on accessor functions is enough to fix this bug. Although 2 bytes is enough, I use 4 bytes since it have no bad effect and make things more easier. This fix was suggested and tested by Steven in his original report. Signed-off-by: Joonsoo Kim <[email protected]> Reported-and-acked-by: Steven King <[email protected]> Acked-by: Christoph Lameter <[email protected]> Tested-by: James Hogan <[email protected]> Tested-by: David Miller <[email protected]> Cc: Pekka Enberg <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
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