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Subject[PATCH v5 3/9] mm: factor helpers for memory_failure_dev_pagemap
Date
memory_failure_dev_pagemap code is a bit complex before introduce RMAP
feature for fsdax. So it is needed to factor some helper functions to
simplify these code.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
mm/memory-failure.c | 101 +++++++++++++++++++++++++-------------------
1 file changed, 57 insertions(+), 44 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 0143d32bc666..068753911946 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1243,6 +1243,60 @@ static int try_to_split_thp_page(struct page *page, const char *msg)
return 0;
}

+static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
+ struct address_space *mapping, pgoff_t index, int flags)
+{
+ struct to_kill *tk;
+ unsigned long size = 0;
+
+ list_for_each_entry(tk, to_kill, nd)
+ if (tk->size_shift)
+ size = max(size, 1UL << tk->size_shift);
+ if (size) {
+ /*
+ * Unmap the largest mapping to avoid breaking up device-dax
+ * mappings which are constant size. The actual size of the
+ * mapping being torn down is communicated in siginfo, see
+ * kill_proc()
+ */
+ loff_t start = (index << PAGE_SHIFT) & ~(size - 1);
+
+ unmap_mapping_range(mapping, start, size, 0);
+ }
+
+ kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags);
+}
+
+static int mf_generic_kill_procs(unsigned long long pfn, int flags)
+{
+ struct page *page = pfn_to_page(pfn);
+ LIST_HEAD(to_kill);
+ dax_entry_t cookie;
+
+ /*
+ * Prevent the inode from being freed while we are interrogating
+ * the address_space, typically this would be handled by
+ * lock_page(), but dax pages do not use the page lock. This
+ * also prevents changes to the mapping of this pfn until
+ * poison signaling is complete.
+ */
+ cookie = dax_lock_page(page);
+ if (!cookie)
+ return -EBUSY;
+ /*
+ * Unlike System-RAM there is no possibility to swap in a
+ * different physical page at a given virtual address, so all
+ * userspace consumption of ZONE_DEVICE memory necessitates
+ * SIGBUS (i.e. MF_MUST_KILL)
+ */
+ flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
+ collect_procs(page, &to_kill, flags & MF_ACTION_REQUIRED);
+
+ unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
+ dax_unlock_page(page, cookie);
+ return 0;
+}
+
static int memory_failure_hugetlb(unsigned long pfn, int flags)
{
struct page *p = pfn_to_page(pfn);
@@ -1323,13 +1377,8 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
struct dev_pagemap *pgmap)
{
struct page *page = pfn_to_page(pfn);
- const bool unmap_success = true;
- unsigned long size = 0;
- struct to_kill *tk;
LIST_HEAD(tokill);
int rc = -EBUSY;
- loff_t start;
- dax_entry_t cookie;

if (flags & MF_COUNT_INCREASED)
/*
@@ -1343,20 +1392,9 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
goto out;
}

- /*
- * Prevent the inode from being freed while we are interrogating
- * the address_space, typically this would be handled by
- * lock_page(), but dax pages do not use the page lock. This
- * also prevents changes to the mapping of this pfn until
- * poison signaling is complete.
- */
- cookie = dax_lock_page(page);
- if (!cookie)
- goto out;
-
if (hwpoison_filter(page)) {
rc = 0;
- goto unlock;
+ goto out;
}

if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
@@ -1364,7 +1402,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
* TODO: Handle HMM pages which may need coordination
* with device-side memory.
*/
- goto unlock;
+ goto out;
}

/*
@@ -1373,32 +1411,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
*/
SetPageHWPoison(page);

- /*
- * Unlike System-RAM there is no possibility to swap in a
- * different physical page at a given virtual address, so all
- * userspace consumption of ZONE_DEVICE memory necessitates
- * SIGBUS (i.e. MF_MUST_KILL)
- */
- flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
- collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED);
-
- list_for_each_entry(tk, &tokill, nd)
- if (tk->size_shift)
- size = max(size, 1UL << tk->size_shift);
- if (size) {
- /*
- * Unmap the largest mapping to avoid breaking up
- * device-dax mappings which are constant size. The
- * actual size of the mapping being torn down is
- * communicated in siginfo, see kill_proc()
- */
- start = (page->index << PAGE_SHIFT) & ~(size - 1);
- unmap_mapping_range(page->mapping, start, size, 0);
- }
- kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, pfn, flags);
- rc = 0;
-unlock:
- dax_unlock_page(page, cookie);
+ mf_generic_kill_procs(pfn, flags);
out:
/* drop pgmap ref acquired in caller */
put_dev_pagemap(pgmap);
--
2.32.0


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