2018-01-18 00:08:09

by Jan H. Schönherr

Subject: [PATCH 1/2] mm: Fix memory size alignment in devm_memremap_pages_release()

The functions devm_memremap_pages() and devm_memremap_pages_release() use
different ways to calculate the section-aligned amount of memory. The
latter function may use an incorrect size if the memory region is small
but straddles a section border.

Use the same code for both.

Fixes: 5f29a77cd957 ("mm: fix mixed zone detection in devm_memremap_pages")
Signed-off-by: Jan H. Schönherr <[email protected]>
---
kernel/memremap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 403ab9c..4712ce6 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -301,7 +301,8 @@ static void devm_memremap_pages_release(struct device *dev, void *data)

/* pages are dead and unused, undo the arch mapping */
align_start = res->start & ~(SECTION_SIZE - 1);
- align_size = ALIGN(resource_size(res), SECTION_SIZE);
+ align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
+ - align_start;

mem_hotplug_begin();
arch_remove_memory(align_start, align_size);
--
2.9.3.1.gcba166c.dirty

2018-01-18 00:08:16

by Jan H. Schönherr

Subject: [PATCH 2/2] mm: Fix devm_memremap_pages() collision handling

If devm_memremap_pages() detects a collision while adding entries
to the radix-tree, we call pgmap_radix_release(). Unfortunately,
the function removes *all* entries for the range -- including the
entries that caused the collision in the first place.

Modify pgmap_radix_release() to take an additional argument to
indicate where to stop, so that only newly added entries are removed
from the tree.

Fixes: 9476df7d80df ("mm: introduce find_dev_pagemap()")
Signed-off-by: Jan H. Schönherr <[email protected]>
---
kernel/memremap.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 4712ce6..2b136d4 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -248,13 +248,16 @@ int device_private_entry_fault(struct vm_area_struct *vma,
EXPORT_SYMBOL(device_private_entry_fault);
#endif /* CONFIG_DEVICE_PRIVATE */

-static void pgmap_radix_release(struct resource *res)
+static void pgmap_radix_release(struct resource *res, unsigned long end_pgoff)
{
unsigned long pgoff, order;

mutex_lock(&pgmap_lock);
- foreach_order_pgoff(res, order, pgoff)
+ foreach_order_pgoff(res, order, pgoff) {
+ if (pgoff >= end_pgoff)
+ break;
radix_tree_delete(&pgmap_radix, PHYS_PFN(res->start) + pgoff);
+ }
mutex_unlock(&pgmap_lock);

synchronize_rcu();
@@ -309,7 +312,7 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
mem_hotplug_done();

untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
- pgmap_radix_release(res);
+ pgmap_radix_release(res, -1);
dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
"%s: failed to free all reserved pages\n", __func__);
}
@@ -459,7 +462,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
err_pfn_remap:
err_radix:
- pgmap_radix_release(res);
+ pgmap_radix_release(res, pgoff);
devres_free(page_map);
return ERR_PTR(error);
}
--
2.9.3.1.gcba166c.dirty

2018-01-20 00:17:22

by Dan Williams

Subject: Re: [PATCH 1/2] mm: Fix memory size alignment in devm_memremap_pages_release()

On Wed, Jan 17, 2018 at 4:06 PM, Jan H. Schönherr <[email protected]> wrote:
> The functions devm_memremap_pages() and devm_memremap_pages_release() use
> different ways to calculate the section-aligned amount of memory. The
> latter function may use an incorrect size if the memory region is small
> but straddles a section border.
>
> Use the same code for both.
>
> Fixes: 5f29a77cd957 ("mm: fix mixed zone detection in devm_memremap_pages")
> Signed-off-by: Jan H. Schönherr <[email protected]>

Looks good to me, applied for 4.16.

2018-01-20 00:18:33

by Dan Williams

Subject: Re: [PATCH 2/2] mm: Fix devm_memremap_pages() collision handling

On Wed, Jan 17, 2018 at 4:06 PM, Jan H. Schönherr <[email protected]> wrote:
> If devm_memremap_pages() detects a collision while adding entries
> to the radix-tree, we call pgmap_radix_release(). Unfortunately,
> the function removes *all* entries for the range -- including the
> entries that caused the collision in the first place.
>
> Modify pgmap_radix_release() to take an additional argument to
> indicate where to stop, so that only newly added entries are removed
> from the tree.
>
> Fixes: 9476df7d80df ("mm: introduce find_dev_pagemap()")
> Signed-off-by: Jan H. Schönherr <[email protected]>

Looks good to me, applied for 4.16.