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![Heiko Carstens](/assets/img/avatar_default.png)
Commitbfc8c90139
("mem-hotplug: implement get/put_online_mems") introduced new functions get/put_online_mems() and mem_hotplug_begin/end() in order to allow similar semantics for memory hotplug like for cpu hotplug. The corresponding functions for cpu hotplug are get/put_online_cpus() and cpu_hotplug_begin/done() for cpu hotplug. The commit however missed to introduce functions that would serialize memory hotplug operations like they are done for cpu hotplug with cpu_maps_update_begin/done(). This basically leaves mem_hotplug.active_writer unprotected and allows concurrent writers to modify it, which may lead to problems as outlined by commitf931ab479d
("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}"). That commit was extended again with commitb5d24fda9c
("mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}") which serializes memory hotplug operations for some call sites by using the device_hotplug lock. In addition with commit3fc2192410
("mm: validate device_hotplug is held for memory hotplug") a sanity check was added to mem_hotplug_begin() to verify that the device_hotplug lock is held. This in turn triggers the following warning on s390: WARNING: CPU: 6 PID: 1 at drivers/base/core.c:643 assert_held_device_hotplug+0x4a/0x58 Call Trace: assert_held_device_hotplug+0x40/0x58) mem_hotplug_begin+0x34/0xc8 add_memory_resource+0x7e/0x1f8 add_memory+0xda/0x130 add_memory_merged+0x15c/0x178 sclp_detect_standby_memory+0x2ae/0x2f8 do_one_initcall+0xa2/0x150 kernel_init_freeable+0x228/0x2d8 kernel_init+0x2a/0x140 kernel_thread_starter+0x6/0xc One possible fix would be to add more lock_device_hotplug() and unlock_device_hotplug() calls around each call site of mem_hotplug_begin/end(). But that would give the device_hotplug lock additional semantics it better should not have (serialize memory hotplug operations). Instead add a new memory_add_remove_lock which has the similar semantics like cpu_add_remove_lock for cpu hotplug. To keep things hopefully a bit easier the lock will be locked and unlocked within the mem_hotplug_begin/end() functions. Link: http://lkml.kernel.org/r/20170314125226.16779-2-heiko.carstens@de.ibm.com Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Acked-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
432 lines
12 KiB
C
432 lines
12 KiB
C
/*
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* Copyright(c) 2015 Intel Corporation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/radix-tree.h>
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#include <linux/memremap.h>
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#include <linux/device.h>
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#include <linux/types.h>
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#include <linux/pfn_t.h>
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#include <linux/io.h>
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#include <linux/mm.h>
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#include <linux/memory_hotplug.h>
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#ifndef ioremap_cache
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/* temporary while we convert existing ioremap_cache users to memremap */
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__weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
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{
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return ioremap(offset, size);
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}
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#endif
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#ifndef arch_memremap_wb
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static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
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{
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return (__force void *)ioremap_cache(offset, size);
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}
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#endif
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static void *try_ram_remap(resource_size_t offset, size_t size)
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{
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unsigned long pfn = PHYS_PFN(offset);
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/* In the simple case just return the existing linear address */
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if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)))
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return __va(offset);
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return NULL; /* fallback to arch_memremap_wb */
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}
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/**
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* memremap() - remap an iomem_resource as cacheable memory
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* @offset: iomem resource start address
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* @size: size of remap
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* @flags: any of MEMREMAP_WB, MEMREMAP_WT and MEMREMAP_WC
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*
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* memremap() is "ioremap" for cases where it is known that the resource
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* being mapped does not have i/o side effects and the __iomem
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* annotation is not applicable. In the case of multiple flags, the different
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* mapping types will be attempted in the order listed below until one of
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* them succeeds.
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*
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* MEMREMAP_WB - matches the default mapping for System RAM on
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* the architecture. This is usually a read-allocate write-back cache.
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* Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
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* memremap() will bypass establishing a new mapping and instead return
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* a pointer into the direct map.
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*
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* MEMREMAP_WT - establish a mapping whereby writes either bypass the
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* cache or are written through to memory and never exist in a
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* cache-dirty state with respect to program visibility. Attempts to
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* map System RAM with this mapping type will fail.
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*
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* MEMREMAP_WC - establish a writecombine mapping, whereby writes may
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* be coalesced together (e.g. in the CPU's write buffers), but is otherwise
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* uncached. Attempts to map System RAM with this mapping type will fail.
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*/
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void *memremap(resource_size_t offset, size_t size, unsigned long flags)
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{
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int is_ram = region_intersects(offset, size,
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IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
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void *addr = NULL;
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if (!flags)
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return NULL;
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if (is_ram == REGION_MIXED) {
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WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
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&offset, (unsigned long) size);
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return NULL;
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}
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/* Try all mapping types requested until one returns non-NULL */
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if (flags & MEMREMAP_WB) {
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/*
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* MEMREMAP_WB is special in that it can be satisifed
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* from the direct map. Some archs depend on the
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* capability of memremap() to autodetect cases where
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* the requested range is potentially in System RAM.
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*/
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if (is_ram == REGION_INTERSECTS)
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addr = try_ram_remap(offset, size);
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if (!addr)
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addr = arch_memremap_wb(offset, size);
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}
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/*
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* If we don't have a mapping yet and other request flags are
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* present then we will be attempting to establish a new virtual
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* address mapping. Enforce that this mapping is not aliasing
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* System RAM.
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*/
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if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
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WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
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&offset, (unsigned long) size);
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return NULL;
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}
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if (!addr && (flags & MEMREMAP_WT))
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addr = ioremap_wt(offset, size);
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if (!addr && (flags & MEMREMAP_WC))
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addr = ioremap_wc(offset, size);
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return addr;
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}
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EXPORT_SYMBOL(memremap);
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void memunmap(void *addr)
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{
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if (is_vmalloc_addr(addr))
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iounmap((void __iomem *) addr);
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}
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EXPORT_SYMBOL(memunmap);
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static void devm_memremap_release(struct device *dev, void *res)
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{
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memunmap(*(void **)res);
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}
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static int devm_memremap_match(struct device *dev, void *res, void *match_data)
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{
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return *(void **)res == match_data;
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}
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void *devm_memremap(struct device *dev, resource_size_t offset,
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size_t size, unsigned long flags)
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{
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void **ptr, *addr;
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ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
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dev_to_node(dev));
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if (!ptr)
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return ERR_PTR(-ENOMEM);
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addr = memremap(offset, size, flags);
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if (addr) {
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*ptr = addr;
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devres_add(dev, ptr);
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} else {
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devres_free(ptr);
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return ERR_PTR(-ENXIO);
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}
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return addr;
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}
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EXPORT_SYMBOL(devm_memremap);
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void devm_memunmap(struct device *dev, void *addr)
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{
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WARN_ON(devres_release(dev, devm_memremap_release,
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devm_memremap_match, addr));
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}
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EXPORT_SYMBOL(devm_memunmap);
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#ifdef CONFIG_ZONE_DEVICE
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static DEFINE_MUTEX(pgmap_lock);
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static RADIX_TREE(pgmap_radix, GFP_KERNEL);
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#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
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#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
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struct page_map {
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struct resource res;
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struct percpu_ref *ref;
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struct dev_pagemap pgmap;
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struct vmem_altmap altmap;
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};
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void get_zone_device_page(struct page *page)
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{
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percpu_ref_get(page->pgmap->ref);
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}
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EXPORT_SYMBOL(get_zone_device_page);
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void put_zone_device_page(struct page *page)
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{
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put_dev_pagemap(page->pgmap);
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}
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EXPORT_SYMBOL(put_zone_device_page);
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static void pgmap_radix_release(struct resource *res)
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{
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resource_size_t key, align_start, align_size, align_end;
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align_start = res->start & ~(SECTION_SIZE - 1);
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align_size = ALIGN(resource_size(res), SECTION_SIZE);
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align_end = align_start + align_size - 1;
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mutex_lock(&pgmap_lock);
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for (key = res->start; key <= res->end; key += SECTION_SIZE)
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radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);
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mutex_unlock(&pgmap_lock);
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}
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static unsigned long pfn_first(struct page_map *page_map)
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{
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struct dev_pagemap *pgmap = &page_map->pgmap;
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const struct resource *res = &page_map->res;
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struct vmem_altmap *altmap = pgmap->altmap;
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unsigned long pfn;
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pfn = res->start >> PAGE_SHIFT;
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if (altmap)
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pfn += vmem_altmap_offset(altmap);
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return pfn;
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}
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static unsigned long pfn_end(struct page_map *page_map)
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{
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const struct resource *res = &page_map->res;
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return (res->start + resource_size(res)) >> PAGE_SHIFT;
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}
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#define for_each_device_pfn(pfn, map) \
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for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
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static void devm_memremap_pages_release(struct device *dev, void *data)
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{
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struct page_map *page_map = data;
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struct resource *res = &page_map->res;
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resource_size_t align_start, align_size;
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struct dev_pagemap *pgmap = &page_map->pgmap;
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if (percpu_ref_tryget_live(pgmap->ref)) {
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dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
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percpu_ref_put(pgmap->ref);
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}
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/* pages are dead and unused, undo the arch mapping */
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align_start = res->start & ~(SECTION_SIZE - 1);
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align_size = ALIGN(resource_size(res), SECTION_SIZE);
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mem_hotplug_begin();
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arch_remove_memory(align_start, align_size);
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mem_hotplug_done();
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untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
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pgmap_radix_release(res);
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dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
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"%s: failed to free all reserved pages\n", __func__);
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}
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/* assumes rcu_read_lock() held at entry */
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struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
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{
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struct page_map *page_map;
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WARN_ON_ONCE(!rcu_read_lock_held());
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page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);
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return page_map ? &page_map->pgmap : NULL;
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}
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/**
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* devm_memremap_pages - remap and provide memmap backing for the given resource
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* @dev: hosting device for @res
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* @res: "host memory" address range
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* @ref: a live per-cpu reference count
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* @altmap: optional descriptor for allocating the memmap from @res
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*
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* Notes:
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* 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
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* (or devm release event).
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*
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* 2/ @res is expected to be a host memory range that could feasibly be
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* treated as a "System RAM" range, i.e. not a device mmio range, but
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* this is not enforced.
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*/
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void *devm_memremap_pages(struct device *dev, struct resource *res,
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struct percpu_ref *ref, struct vmem_altmap *altmap)
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{
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resource_size_t key, align_start, align_size, align_end;
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pgprot_t pgprot = PAGE_KERNEL;
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struct dev_pagemap *pgmap;
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struct page_map *page_map;
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int error, nid, is_ram;
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unsigned long pfn;
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align_start = res->start & ~(SECTION_SIZE - 1);
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align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
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- align_start;
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is_ram = region_intersects(align_start, align_size,
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IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
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if (is_ram == REGION_MIXED) {
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WARN_ONCE(1, "%s attempted on mixed region %pr\n",
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__func__, res);
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return ERR_PTR(-ENXIO);
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}
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if (is_ram == REGION_INTERSECTS)
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return __va(res->start);
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if (!ref)
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return ERR_PTR(-EINVAL);
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page_map = devres_alloc_node(devm_memremap_pages_release,
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sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
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if (!page_map)
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return ERR_PTR(-ENOMEM);
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pgmap = &page_map->pgmap;
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memcpy(&page_map->res, res, sizeof(*res));
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pgmap->dev = dev;
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if (altmap) {
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memcpy(&page_map->altmap, altmap, sizeof(*altmap));
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pgmap->altmap = &page_map->altmap;
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}
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pgmap->ref = ref;
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pgmap->res = &page_map->res;
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mutex_lock(&pgmap_lock);
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error = 0;
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align_end = align_start + align_size - 1;
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for (key = align_start; key <= align_end; key += SECTION_SIZE) {
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struct dev_pagemap *dup;
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rcu_read_lock();
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dup = find_dev_pagemap(key);
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rcu_read_unlock();
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if (dup) {
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dev_err(dev, "%s: %pr collides with mapping for %s\n",
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__func__, res, dev_name(dup->dev));
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error = -EBUSY;
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break;
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}
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error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,
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page_map);
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if (error) {
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dev_err(dev, "%s: failed: %d\n", __func__, error);
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break;
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}
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}
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mutex_unlock(&pgmap_lock);
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if (error)
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goto err_radix;
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nid = dev_to_node(dev);
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if (nid < 0)
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nid = numa_mem_id();
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error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0,
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align_size);
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if (error)
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goto err_pfn_remap;
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mem_hotplug_begin();
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error = arch_add_memory(nid, align_start, align_size, true);
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mem_hotplug_done();
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if (error)
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goto err_add_memory;
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for_each_device_pfn(pfn, page_map) {
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struct page *page = pfn_to_page(pfn);
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/*
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* ZONE_DEVICE pages union ->lru with a ->pgmap back
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* pointer. It is a bug if a ZONE_DEVICE page is ever
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* freed or placed on a driver-private list. Seed the
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* storage with LIST_POISON* values.
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*/
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list_del(&page->lru);
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page->pgmap = pgmap;
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}
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devres_add(dev, page_map);
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return __va(res->start);
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err_add_memory:
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untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
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err_pfn_remap:
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err_radix:
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pgmap_radix_release(res);
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devres_free(page_map);
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return ERR_PTR(error);
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}
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EXPORT_SYMBOL(devm_memremap_pages);
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unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
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{
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/* number of pfns from base where pfn_to_page() is valid */
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return altmap->reserve + altmap->free;
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}
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void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
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{
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altmap->alloc -= nr_pfns;
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}
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struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
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{
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/*
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* 'memmap_start' is the virtual address for the first "struct
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* page" in this range of the vmemmap array. In the case of
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* CONFIG_SPARSEMEM_VMEMMAP a page_to_pfn conversion is simple
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* pointer arithmetic, so we can perform this to_vmem_altmap()
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* conversion without concern for the initialization state of
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* the struct page fields.
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*/
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struct page *page = (struct page *) memmap_start;
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struct dev_pagemap *pgmap;
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/*
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* Unconditionally retrieve a dev_pagemap associated with the
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* given physical address, this is only for use in the
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* arch_{add|remove}_memory() for setting up and tearing down
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* the memmap.
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*/
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rcu_read_lock();
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pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
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rcu_read_unlock();
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return pgmap ? pgmap->altmap : NULL;
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}
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#endif /* CONFIG_ZONE_DEVICE */
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