Virtual fallbacks are rare and thus subtle bugs may creep in if we do not test the fallbacks. CONFIG_VFALLBACK_ALWAYS makes all vcompound allocations fall back to vmalloc. Signed-off-by: Christoph Lameter --- lib/Kconfig.debug | 11 +++++++++++ mm/vmalloc.c | 18 +++++++++++++++--- 2 files changed, 26 insertions(+), 3 deletions(-) Index: linux-2.6.25-rc5-mm1/lib/Kconfig.debug =================================================================== --- linux-2.6.25-rc5-mm1.orig/lib/Kconfig.debug 2008-03-20 23:05:12.910212550 -0700 +++ linux-2.6.25-rc5-mm1/lib/Kconfig.debug 2008-03-20 23:06:21.599135107 -0700 @@ -158,6 +158,17 @@ config DETECT_SOFTLOCKUP can be detected via the NMI-watchdog, on platforms that support it.) +config VFALLBACK_ALWAYS + bool "Always fall back to virtually mapped compound pages" + default y + help + Virtual compound pages are only allocated if there is no linear + memory available. They are a fallback and errors created by the + use of virtual mappings instead of linear ones may not surface + because of their infrequent use. This option makes every + allocation that allows a fallback to a virtual mapping use + the virtual mapping. May have a significant performance impact. + config SCHED_DEBUG bool "Collect scheduler debugging info" depends on DEBUG_KERNEL && PROC_FS Index: linux-2.6.25-rc5-mm1/mm/vmalloc.c =================================================================== --- linux-2.6.25-rc5-mm1.orig/mm/vmalloc.c 2008-03-20 23:06:14.875045176 -0700 +++ linux-2.6.25-rc5-mm1/mm/vmalloc.c 2008-03-20 23:06:21.599135107 -0700 @@ -1159,7 +1159,13 @@ struct page *alloc_vcompound(gfp_t flags struct vm_struct *vm; struct page *page; - page = alloc_pages(flags | __GFP_NORETRY | __GFP_NOWARN, order); +#ifdef CONFIG_VFALLBACK_ALWAYS + if (system_state == SYSTEM_RUNNING && order) + page = NULL; + else +#endif + page = alloc_pages(flags | __GFP_NORETRY | __GFP_NOWARN, + order); if (page || !order) return page; @@ -1175,8 +1181,14 @@ void *__alloc_vcompound(gfp_t flags, int struct vm_struct *vm; void *addr; - addr = (void *)__get_free_pages(flags | __GFP_NORETRY | __GFP_NOWARN, - order); +#ifdef CONFIG_VFALLBACK_ALWAYS + if (system_state == SYSTEM_RUNNING && order) + addr = NULL; + else +#endif + addr = (void *)__get_free_pages( + flags | __GFP_NORETRY | __GFP_NOWARN, order); + if (addr || !order) return addr; -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/