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| author | Dan Williams <dan.j.williams@intel.com> | 2016-01-29 21:48:34 -0800 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2016-01-29 21:54:04 -0800 |
| commit | eb7d78c9e7f6418932bd5fbee45eb46d5ab05002 (patch) | |
| tree | 394076599244a296f4f5b57c3e1e5fabbd40cf8f /kernel/memremap.c | |
| parent | 45eb570a0db3391c88cba04510a20fe7e4125497 (diff) | |
| download | lwn-eb7d78c9e7f6418932bd5fbee45eb46d5ab05002.tar.gz lwn-eb7d78c9e7f6418932bd5fbee45eb46d5ab05002.zip | |
devm_memremap_pages: fix vmem_altmap lifetime + alignment handling
to_vmem_altmap() needs to return valid results until
arch_remove_memory() completes. It also needs to be valid for any pfn
in a section regardless of whether that pfn maps to data. This escape
was a result of a bug in the unit test.
The signature of this bug is that free_pagetable() fails to retrieve a
vmem_altmap and goes off into the weeds:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff811d2629>] get_pfnblock_flags_mask+0x49/0x60
[..]
Call Trace:
[<ffffffff811d3477>] free_hot_cold_page+0x97/0x1d0
[<ffffffff811d367a>] __free_pages+0x2a/0x40
[<ffffffff8191e669>] free_pagetable+0x8c/0xd4
[<ffffffff8191ef4e>] remove_pagetable+0x37a/0x808
[<ffffffff8191b210>] vmemmap_free+0x10/0x20
Fixes: 4b94ffdc4163 ("x86, mm: introduce vmem_altmap to augment vmemmap_populate()")
Cc: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'kernel/memremap.c')
| -rw-r--r-- | kernel/memremap.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c index e517a16cb426..cbc3e97e2bb4 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -183,7 +183,11 @@ EXPORT_SYMBOL(put_zone_device_page); static void pgmap_radix_release(struct resource *res) { - resource_size_t key; + resource_size_t key, align_start, align_size, align_end; + + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(resource_size(res), SECTION_SIZE); + align_end = align_start + align_size - 1; mutex_lock(&pgmap_lock); for (key = res->start; key <= res->end; key += SECTION_SIZE) @@ -226,12 +230,11 @@ static void devm_memremap_pages_release(struct device *dev, void *data) percpu_ref_put(pgmap->ref); } - pgmap_radix_release(res); - /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(resource_size(res), SECTION_SIZE); arch_remove_memory(align_start, align_size); + pgmap_radix_release(res); dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc, "%s: failed to free all reserved pages\n", __func__); } @@ -267,7 +270,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, { int is_ram = region_intersects(res->start, resource_size(res), "System RAM"); - resource_size_t key, align_start, align_size; + resource_size_t key, align_start, align_size, align_end; struct dev_pagemap *pgmap; struct page_map *page_map; unsigned long pfn; @@ -309,7 +312,10 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, mutex_lock(&pgmap_lock); error = 0; - for (key = res->start; key <= res->end; key += SECTION_SIZE) { + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(resource_size(res), SECTION_SIZE); + align_end = align_start + align_size - 1; + for (key = align_start; key <= align_end; key += SECTION_SIZE) { struct dev_pagemap *dup; rcu_read_lock(); @@ -336,8 +342,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, if (nid < 0) nid = numa_mem_id(); - align_start = res->start & ~(SECTION_SIZE - 1); - align_size = ALIGN(resource_size(res), SECTION_SIZE); error = arch_add_memory(nid, align_start, align_size, true); if (error) goto err_add_memory; |