From e7638488434415aa478e78435cac8f0365737638 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 16 May 2018 11:46:08 -0700 Subject: mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In preparation for fixing dax-dma-vs-unmap issues, filesystems need to be able to rely on the fact that they will get wakeups on dev_pagemap page-idle events. Introduce MEMORY_DEVICE_FS_DAX and generic_dax_page_free() as common indicator / infrastructure for dax filesytems to require. With this change there are no users of the MEMORY_DEVICE_HOST designation, so remove it. The HMM sub-system extended dev_pagemap to arrange a callback when a dev_pagemap managed page is freed. Since a dev_pagemap page is free / idle when its reference count is 1 it requires an additional branch to check the page-type at put_page() time. Given put_page() is a hot-path we do not want to incur that check if HMM is not in use, so a static branch is used to avoid that overhead when not necessary. Now, the FS_DAX implementation wants to reuse this mechanism for receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific static-key into a generic mechanism that either HMM or FS_DAX code paths can enable. For ARCH=um builds, and any other arch that lacks ZONE_DEVICE support, care must be taken to compile out the DEV_PAGEMAP_OPS infrastructure. However, we still need to support FS_DAX in the FS_DAX_LIMITED case implemented by the s390/dcssblk driver. Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Michal Hocko Reported-by: kbuild test robot Reported-by: Thomas Meyer Reported-by: Dave Jiang Cc: "Jérôme Glisse" Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig Signed-off-by: Dan Williams --- mm/hmm.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) (limited to 'mm/hmm.c') diff --git a/mm/hmm.c b/mm/hmm.c index 486dc394a5a3..de7b6bf77201 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -35,15 +35,6 @@ #define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT) -#if defined(CONFIG_DEVICE_PRIVATE) || defined(CONFIG_DEVICE_PUBLIC) -/* - * Device private memory see HMM (Documentation/vm/hmm.txt) or hmm.h - */ -DEFINE_STATIC_KEY_FALSE(device_private_key); -EXPORT_SYMBOL(device_private_key); -#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */ - - #if IS_ENABLED(CONFIG_HMM_MIRROR) static const struct mmu_notifier_ops hmm_mmu_notifier_ops; @@ -1167,7 +1158,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, resource_size_t addr; int ret; - static_branch_enable(&device_private_key); + dev_pagemap_get_ops(); devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), GFP_KERNEL, dev_to_node(device)); @@ -1261,7 +1252,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY) return ERR_PTR(-EINVAL); - static_branch_enable(&device_private_key); + dev_pagemap_get_ops(); devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), GFP_KERNEL, dev_to_node(device)); -- cgit v1.2.1