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charset="utf-8" The elfcorehdr descirbes the dumpable region in PT_LOADs. Generally, an iomem resource registered with flags (IORESOURCE_SYSTEM_RAM | IORESOUCE_BUSY) will be added to PT_LOADs by kexe_file_load(2). An iomem resource with name prefix "System RAM" will be added to PT_LOADs in kexec-tools by calling kexe_load(2). So a simple way to make the altmap dumpable is to register altmap region as a separate resource with the proper name and resource flags. Here naming it as "Device Backed Vmemmap" plus resource flags (IORESOURCE_DEVICE_BACKED_VMEMMAP and IORESOUCE_BUSY) to make it work first. A /proc/iomem example is as following: $ sudo cat /proc/iomem ... fffc0000-ffffffff : Reserved 100000000-13fffffff : Persistent Memory 100000000-10fffffff : namespace0.0 100000000-1005fffff : Device Backed Vmemmap # fsdax a80000000-b7fffffff : CXL Window 0 a80000000-affffffff : Persistent Memory a80000000-affffffff : region1 a80000000-a811fffff : namespace1.0 a80000000-a811fffff : Device Backed Vmemmap # devdax a81200000-abfffffff : dax1.0 b80000000-c7fffffff : CXL Window 1 c80000000-147fffffff : PCI Bus 0000:00 c80000000-c801fffff : PCI Bus 0000:01 ... CC: Andrew Morton CC: Greg Kroah-Hartman CC: Baoquan He CC: Dan Williams CC: linux-mm@kvack.org Signed-off-by: Li Zhijian --- include/linux/ioport.h | 1 + include/linux/memremap.h | 3 +++ mm/memremap.c | 23 ++++++++++++++++++++++- 3 files changed, 26 insertions(+), 1 deletion(-) diff --git a/include/linux/ioport.h b/include/linux/ioport.h index db7fe25f3370..3b59e924f531 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -69,6 +69,7 @@ struct resource { #define IORESOURCE_UNSET 0x20000000 /* No address assigned yet */ #define IORESOURCE_AUTO 0x40000000 #define IORESOURCE_BUSY 0x80000000 /* Driver has marked this resource bus= y */ +#define IORESOURCE_DEVICE_BACKED_VMEMMAP 0xa0000000 /* device backed vmemm= ap resource */ =20 /* I/O resource extended types */ #define IORESOURCE_SYSTEM_RAM (IORESOURCE_MEM|IORESOURCE_SYSRAM) diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 744c830f4b13..ca1f12353008 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -17,6 +17,8 @@ struct device; * @free: free pages set aside in the mapping for memmap storage * @align: pages reserved to meet allocation alignments * @alloc: track pages consumed, private to vmemmap_populate() + * @parent: the parent resource that altmap region belongs to + * @res: altmap region resource */ struct vmem_altmap { unsigned long base_pfn; @@ -25,6 +27,7 @@ struct vmem_altmap { unsigned long free; unsigned long align; unsigned long alloc; + struct resource *parent, *res; }; =20 /* diff --git a/mm/memremap.c b/mm/memremap.c index 9e9fb1972fff..78047157b0ee 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -157,7 +157,17 @@ EXPORT_SYMBOL_GPL(memunmap_pages); =20 static void devm_memremap_pages_release(void *data) { - memunmap_pages(data); + struct dev_pagemap *pgmap =3D data; + + if (pgmap->flags & PGMAP_ALTMAP_VALID && pgmap->altmap.res) { + resource_size_t start =3D pgmap->altmap.res->start; + resource_size_t size =3D pgmap->altmap.res->end - + pgmap->altmap.res->start + 1; + + __release_region(pgmap->altmap.parent, start, size); + } + + memunmap_pages(pgmap); } =20 static void dev_pagemap_percpu_release(struct percpu_ref *ref) @@ -404,11 +414,22 @@ void *devm_memremap_pages(struct device *dev, struct = dev_pagemap *pgmap) { int error; void *ret; + struct vmem_altmap *altmap =3D &pgmap->altmap; =20 ret =3D memremap_pages(pgmap, dev_to_node(dev)); if (IS_ERR(ret)) return ret; =20 + if (pgmap->flags & PGMAP_ALTMAP_VALID && altmap->parent) { + unsigned long start =3D altmap->base_pfn << PAGE_SHIFT; + unsigned long size =3D vmem_altmap_offset(altmap) << PAGE_SHIFT; + int flags =3D IORESOURCE_DEVICE_BACKED_VMEMMAP | IORESOURCE_BUSY; + + altmap->res =3D __request_region(altmap->parent, start, size, + "Device Backed Vmemmap", flags); + pr_debug("Insert a separate resource for altmap, %lx-%lx\n", + start, start + size); + } error =3D devm_add_action_or_reset(dev, devm_memremap_pages_release, pgmap); if (error) --=20 2.29.2