From eb33575cf67d3f35fa2510210ef92631266e2465 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Wed, 13 May 2009 17:34:48 +0100 Subject: [ARM] Double check memmap is actually valid with a memmap has unexpected holes V2 pfn_valid() is meant to be able to tell if a given PFN has valid memmap associated with it or not. In FLATMEM, it is expected that holes always have valid memmap as long as there is valid PFNs either side of the hole. In SPARSEMEM, it is assumed that a valid section has a memmap for the entire section. However, ARM and maybe other embedded architectures in the future free memmap backing holes to save memory on the assumption the memmap is never used. The page_zone linkages are then broken even though pfn_valid() returns true. A walker of the full memmap must then do this additional check to ensure the memmap they are looking at is sane by making sure the zone and PFN linkages are still valid. This is expensive, but walkers of the full memmap are extremely rare. This was caught before for FLATMEM and hacked around but it hits again for SPARSEMEM because the page_zone linkages can look ok where the PFN linkages are totally screwed. This looks like a hatchet job but the reality is that any clean solution would end up consumning all the memory saved by punching these unexpected holes in the memmap. For example, we tried marking the memmap within the section invalid but the section size exceeds the size of the hole in most cases so pfn_valid() starts returning false where valid memmap exists. Shrinking the size of the section would increase memory consumption offsetting the gains. This patch identifies when an architecture is punching unexpected holes in the memmap that the memory model cannot automatically detect and sets ARCH_HAS_HOLES_MEMORYMODEL. At the moment, this is restricted to EP93xx which is the model sub-architecture this has been reported on but may expand later. When set, walkers of the full memmap must call memmap_valid_within() for each PFN and passing in what it expects the page and zone to be for that PFN. If it finds the linkages to be broken, it assumes the memmap is invalid for that PFN. Signed-off-by: Mel Gorman Signed-off-by: Russell King --- include/linux/mmzone.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'include') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 186ec6ab334d..a47c879e1304 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1097,6 +1097,32 @@ unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long); #define pfn_valid_within(pfn) (1) #endif +#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL +/* + * pfn_valid() is meant to be able to tell if a given PFN has valid memmap + * associated with it or not. In FLATMEM, it is expected that holes always + * have valid memmap as long as there is valid PFNs either side of the hole. + * In SPARSEMEM, it is assumed that a valid section has a memmap for the + * entire section. + * + * However, an ARM, and maybe other embedded architectures in the future + * free memmap backing holes to save memory on the assumption the memmap is + * never used. The page_zone linkages are then broken even though pfn_valid() + * returns true. A walker of the full memmap must then do this additional + * check to ensure the memmap they are looking at is sane by making sure + * the zone and PFN linkages are still valid. This is expensive, but walkers + * of the full memmap are extremely rare. + */ +int memmap_valid_within(unsigned long pfn, + struct page *page, struct zone *zone); +#else +static inline int memmap_valid_within(unsigned long pfn, + struct page *page, struct zone *zone) +{ + return 1; +} +#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */ + #endif /* !__GENERATING_BOUNDS.H */ #endif /* !__ASSEMBLY__ */ #endif /* _LINUX_MMZONE_H */ -- cgit v1.2.2 From 03fbdb15c14e9746c63168e3ff2c64b9c8336d33 Mon Sep 17 00:00:00 2001 From: Alessandro Rubini Date: Wed, 20 May 2009 22:39:08 +0100 Subject: [ARM] 5519/1: amba probe: pass "struct amba_id *" instead of void * The second argument of the probe method points to the amba_id structure, so it's better passed with the correct type. None of the current in-tree drivers uses the pointer, so they have only been checked for a clean compile. Change suggested by Russell King. Signed-off-by: Alessandro Rubini Signed-off-by: Russell King --- include/linux/amba/bus.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h index 51e6e54b2aa1..9b93cafa82a0 100644 --- a/include/linux/amba/bus.h +++ b/include/linux/amba/bus.h @@ -28,7 +28,7 @@ struct amba_id { struct amba_driver { struct device_driver drv; - int (*probe)(struct amba_device *, void *); + int (*probe)(struct amba_device *, struct amba_id *); int (*remove)(struct amba_device *); void (*shutdown)(struct amba_device *); int (*suspend)(struct amba_device *, pm_message_t); -- cgit v1.2.2