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![Michal Hocko](/assets/img/avatar_default.png)
devm_memremap_pages is initializing struct pages in for_each_device_pfn and that can take quite some time. We have even seen a soft lockup triggering on a non preemptive kernel NMI watchdog: BUG: soft lockup - CPU#61 stuck for 22s! [kworker/u641:11:1808] [...] RIP: 0010:[<ffffffff8118b6b7>] [<ffffffff8118b6b7>] devm_memremap_pages+0x327/0x430 [...] Call Trace: pmem_attach_disk+0x2fd/0x3f0 [nd_pmem] nvdimm_bus_probe+0x64/0x110 [libnvdimm] driver_probe_device+0x1f7/0x420 bus_for_each_drv+0x52/0x80 __device_attach+0xb0/0x130 bus_probe_device+0x87/0xa0 device_add+0x3fc/0x5f0 nd_async_device_register+0xe/0x40 [libnvdimm] async_run_entry_fn+0x43/0x150 process_one_work+0x14e/0x410 worker_thread+0x116/0x490 kthread+0xc7/0xe0 ret_from_fork+0x3f/0x70 fix this by adding cond_resched every 1024 pages. Link: http://lkml.kernel.org/r/20170918121410.24466-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Johannes Thumshirn <jthumshirn@suse.de> Tested-by: Johannes Thumshirn <jthumshirn@suse.de> Cc: Dan Williams <dan.j.williams@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
528 lines
15 KiB
C
528 lines
15 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/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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#include <linux/swap.h>
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#include <linux/swapops.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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#ifndef arch_memremap_can_ram_remap
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static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
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unsigned long flags)
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{
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return true;
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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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unsigned long flags)
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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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arch_memremap_can_ram_remap(offset, size, flags))
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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, MEMREMAP_WC,
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* MEMREMAP_ENC, MEMREMAP_DEC
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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, flags);
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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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static unsigned long order_at(struct resource *res, unsigned long pgoff)
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{
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unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff;
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unsigned long nr_pages, mask;
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nr_pages = PHYS_PFN(resource_size(res));
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if (nr_pages == pgoff)
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return ULONG_MAX;
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/*
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* What is the largest aligned power-of-2 range available from
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* this resource pgoff to the end of the resource range,
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* considering the alignment of the current pgoff?
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*/
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mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff);
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if (!mask)
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return ULONG_MAX;
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return find_first_bit(&mask, BITS_PER_LONG);
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}
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#define foreach_order_pgoff(res, order, pgoff) \
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for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \
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pgoff += 1UL << order, order = order_at((res), pgoff))
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#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
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int device_private_entry_fault(struct vm_area_struct *vma,
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unsigned long addr,
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swp_entry_t entry,
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unsigned int flags,
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pmd_t *pmdp)
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{
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struct page *page = device_private_entry_to_page(entry);
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/*
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* The page_fault() callback must migrate page back to system memory
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* so that CPU can access it. This might fail for various reasons
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* (device issue, device was unsafely unplugged, ...). When such
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* error conditions happen, the callback must return VM_FAULT_SIGBUS.
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*
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* Note that because memory cgroup charges are accounted to the device
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* memory, this should never fail because of memory restrictions (but
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* allocation of regular system page might still fail because we are
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* out of memory).
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*
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* There is a more in-depth description of what that callback can and
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* cannot do, in include/linux/memremap.h
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*/
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return page->pgmap->page_fault(vma, addr, page, flags, pmdp);
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}
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EXPORT_SYMBOL(device_private_entry_fault);
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#endif /* CONFIG_DEVICE_PRIVATE */
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static void pgmap_radix_release(struct resource *res)
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{
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unsigned long pgoff, order;
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mutex_lock(&pgmap_lock);
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foreach_order_pgoff(res, order, pgoff)
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radix_tree_delete(&pgmap_radix, PHYS_PFN(res->start) + pgoff);
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mutex_unlock(&pgmap_lock);
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synchronize_rcu();
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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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unsigned long pfn;
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for_each_device_pfn(pfn, page_map)
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put_page(pfn_to_page(pfn));
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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_PFN(phys));
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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). The expected order of events is that @ref has
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* been through percpu_ref_kill() before devm_memremap_pages_release(). The
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* wait for the completion of all references being dropped and
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* percpu_ref_exit() must occur after devm_memremap_pages_release().
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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 align_start, align_size, align_end;
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unsigned long pfn, pgoff, order;
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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, i = 0;
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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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pgmap->type = MEMORY_DEVICE_HOST;
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pgmap->page_fault = NULL;
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pgmap->page_free = NULL;
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pgmap->data = NULL;
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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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foreach_order_pgoff(res, order, pgoff) {
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struct dev_pagemap *dup;
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rcu_read_lock();
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dup = find_dev_pagemap(res->start + PFN_PHYS(pgoff));
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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,
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PHYS_PFN(res->start) + pgoff, order, 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, false);
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if (!error)
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move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
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align_start >> PAGE_SHIFT,
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align_size >> PAGE_SHIFT);
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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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percpu_ref_get(ref);
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if (!(++i % 1024))
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cond_resched();
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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);
|
|
err_pfn_remap:
|
|
err_radix:
|
|
pgmap_radix_release(res);
|
|
devres_free(page_map);
|
|
return ERR_PTR(error);
|
|
}
|
|
EXPORT_SYMBOL(devm_memremap_pages);
|
|
|
|
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
|
|
{
|
|
/* number of pfns from base where pfn_to_page() is valid */
|
|
return altmap->reserve + altmap->free;
|
|
}
|
|
|
|
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
|
|
{
|
|
altmap->alloc -= nr_pfns;
|
|
}
|
|
|
|
struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
|
|
{
|
|
/*
|
|
* 'memmap_start' is the virtual address for the first "struct
|
|
* page" in this range of the vmemmap array. In the case of
|
|
* CONFIG_SPARSEMEM_VMEMMAP a page_to_pfn conversion is simple
|
|
* pointer arithmetic, so we can perform this to_vmem_altmap()
|
|
* conversion without concern for the initialization state of
|
|
* the struct page fields.
|
|
*/
|
|
struct page *page = (struct page *) memmap_start;
|
|
struct dev_pagemap *pgmap;
|
|
|
|
/*
|
|
* Unconditionally retrieve a dev_pagemap associated with the
|
|
* given physical address, this is only for use in the
|
|
* arch_{add|remove}_memory() for setting up and tearing down
|
|
* the memmap.
|
|
*/
|
|
rcu_read_lock();
|
|
pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
|
|
rcu_read_unlock();
|
|
|
|
return pgmap ? pgmap->altmap : NULL;
|
|
}
|
|
#endif /* CONFIG_ZONE_DEVICE */
|
|
|
|
|
|
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC)
|
|
void put_zone_device_private_or_public_page(struct page *page)
|
|
{
|
|
int count = page_ref_dec_return(page);
|
|
|
|
/*
|
|
* If refcount is 1 then page is freed and refcount is stable as nobody
|
|
* holds a reference on the page.
|
|
*/
|
|
if (count == 1) {
|
|
/* Clear Active bit in case of parallel mark_page_accessed */
|
|
__ClearPageActive(page);
|
|
__ClearPageWaiters(page);
|
|
|
|
page->mapping = NULL;
|
|
mem_cgroup_uncharge(page);
|
|
|
|
page->pgmap->page_free(page, page->pgmap->data);
|
|
} else if (!count)
|
|
__put_page(page);
|
|
}
|
|
EXPORT_SYMBOL(put_zone_device_private_or_public_page);
|
|
#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
|