On Tue, 13 Mar 2007 10:42:02 +0000 [EMAIL PROTECTED] (Mel Gorman) wrote: > There are problems in the use of SPARSEMEM and pageblock flags that causes > problems on ia64. > > The first part of the problem is that units are incorrect in > SECTION_BLOCKFLAGS_BITS computation. This results in a map_section's > section_mem_map being treated as part of a bitmap which isn't good. This > was evident with an invalid virtual address when mem_init attempted to free > bootmem pages while relinquishing control from the bootmem allocator. > > The second part of the problem occurs because the pageblock flags bitmap is > be located with the mem_section. The SECTIONS_PER_ROOT computation using > sizeof (mem_section) may not be a power of 2 depending on the size of the > bitmap. This renders masks and other such things not power of 2 base. This > issue was seen with SPARSEMEM_EXTREME on ia64. This patch moves the bitmap > outside of mem_section and uses a pointer instead in the mem_section. The > bitmaps are allocated when the section is being initialised. > > Note that sparse_early_usemap_alloc() does not use alloc_remap() like > sparse_early_mem_map_alloc(). The allocation required for the bitmap on x86, > the only architecture that uses alloc_remap is typically smaller than a cache > line. alloc_remap() pads out allocations to the cache size which would be > a needless waste. > > Credit to Bob Picco for identifying the original problem and effecting a > fix for the SECTION_BLOCKFLAGS_BITS calculation. Credit to Andy Whitcroft > for devising the best way of allocating the bitmaps only when required for > the section.
SuperH allmodconfig blew up: mm/sparse.c: In function `sparse_init': mm/sparse.c:482: error: implicit declaration of function `sparse_early_usemap_alloc' mm/sparse.c:482: warning: assignment makes pointer from integer without a cast mm/sparse.c: In function `sparse_add_one_section': mm/sparse.c:553: error: implicit declaration of function `__kmalloc_section_usemap' mm/sparse.c:553: warning: assignment makes pointer from integer without a cast - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
