On 2021/1/12 10:55 上午, Ruan Shiyang wrote:

On 2021/1/6 下午11:41, Jan Kara wrote:

quoted

On Thu 31-12-20 00:55:55, Shiyang Ruan wrote:

quoted

The current memory_failure_dev_pagemap() can only handle single-mapped
dax page for fsdax mode.  The dax page could be mapped by multiple 
files
and offsets if we let reflink feature & fsdax mode work together.  So,
we refactor current implementation to support handle memory failure on
each file and offset.

Signed-off-by: Shiyang Ruan <redacted>

Overall this looks OK to me, a few comments below.

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---
  fs/dax.c            | 21 +++++++++++
  include/linux/dax.h |  1 +
  include/linux/mm.h  |  9 +++++
  mm/memory-failure.c | 91 
++++++++++++++++++++++++++++++++++-----------
  4 files changed, 100 insertions(+), 22 deletions(-)

...

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quoted

  @@ -345,9 +348,12 @@ static void add_to_kill(struct task_struct 
*tsk, struct page *p,
      }
        tk->addr = page_address_in_vma(p, vma);
-    if (is_zone_device_page(p))
-        tk->size_shift = dev_pagemap_mapping_shift(p, vma);
-    else
+    if (is_zone_device_page(p)) {
+        if (is_device_fsdax_page(p))
+            tk->addr = vma->vm_start +
+                    ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);

It seems strange to use 'pgoff' for dax pages and not for any other 
page.
Why? I'd rather pass correct pgoff from all callers of add_to_kill() and
avoid this special casing...

Because one fsdax page can be shared by multiple pgoffs.  I have to 
pass each pgoff in each iteration to calculate the address in vma (for 
tk->addr).  Other kinds of pages don't need this. They can get their 
unique address by calling "page_address_in_vma()".

IMO,   an fsdax page can be shared by multiple files rather than 
multiple pgoffs if fs query support reflink.   Because an page only 
located in an mapping(page->mapping is exclusive),  hence it  only has 
an pgoff or index pointing at the node.

  or  I miss something for the feature ?  thanks,

So, I added this fsdax case here.  This patchset only implemented the 
fsdax case, other cases also need to be added here if to be implemented.


-- 
Thanks,
Ruan Shiyang.

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quoted

+        tk->size_shift = dev_pagemap_mapping_shift(p, vma, tk->addr);
+    } else
          tk->size_shift = page_shift(compound_head(p));
        /*

@@ -495,7 +501,7 @@ static void collect_procs_anon(struct page 

*page, struct list_head *to_kill,
              if (!page_mapped_in_vma(page, vma))
                  continue;
              if (vma->vm_mm == t->mm)
-                add_to_kill(t, page, vma, to_kill);
+                add_to_kill(t, page, NULL, 0, vma, to_kill);
          }
      }
      read_unlock(&tasklist_lock);

@@ -505,24 +511,19 @@ static void collect_procs_anon(struct page 

*page, struct list_head *to_kill,
  /*
   * Collect processes when the error hit a file mapped page.
   */
-static void collect_procs_file(struct page *page, struct list_head 
*to_kill,
-                int force_early)
+static void collect_procs_file(struct page *page, struct 
address_space *mapping,
+        pgoff_t pgoff, struct list_head *to_kill, int force_early)
  {
      struct vm_area_struct *vma;
      struct task_struct *tsk;
-    struct address_space *mapping = page->mapping;
-    pgoff_t pgoff;
        i_mmap_lock_read(mapping);
      read_lock(&tasklist_lock);
-    pgoff = page_to_pgoff(page);
      for_each_process(tsk) {
          struct task_struct *t = task_early_kill(tsk, force_early);
-
          if (!t)
              continue;
-        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
-                      pgoff) {
+        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, 
pgoff) {
              /*
               * Send early kill signal to tasks where a vma covers
               * the page but the corrupted page is not necessarily

@@ -531,7 +532,7 @@ static void collect_procs_file(struct page 

*page, struct list_head *to_kill,
               * to be informed of all such data corruptions.
               */
              if (vma->vm_mm == t->mm)
-                add_to_kill(t, page, vma, to_kill);
+                add_to_kill(t, page, mapping, pgoff, vma, to_kill);
          }
      }
      read_unlock(&tasklist_lock);

@@ -550,7 +551,8 @@ static void collect_procs(struct page *page, 

struct list_head *tokill,
      if (PageAnon(page))
          collect_procs_anon(page, tokill, force_early);
      else
-        collect_procs_file(page, tokill, force_early);
+        collect_procs_file(page, page->mapping, page_to_pgoff(page),

Why not use page_mapping() helper here? It would be safer for THPs if 
they
ever get here...

                                Honza