diff mbox series

[v5,02/25] fs/dax: Return unmapped busy pages from dax_layout_busy_page_range()

Message ID db02794f12a4cc8c659a1123bdc90fcb4dcb1104.1736221254.git-series.apopple@nvidia.com (mailing list archive)
State Handled Elsewhere
Headers show
Series fs/dax: Fix ZONE_DEVICE page reference counts | expand

Commit Message

Alistair Popple Jan. 7, 2025, 3:42 a.m. UTC 
dax_layout_busy_page_range() is used by file systems to scan the DAX
page-cache to unmap mapping pages from user-space and to determine if
any pages in the given range are busy, either due to ongoing DMA or
other get_user_pages() usage.

Currently it checks to see the file mapping is mapped into user-space
with mapping_mapped() and returns early if not, skipping the check for
DMA busy pages. This is wrong as pages may still be undergoing DMA
access even if they have subsequently been unmapped from
user-space. Fix this by dropping the check for mapping_mapped().

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/dax.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Dan Williams Jan. 8, 2025, 10:30 p.m. UTC | #1 
Alistair Popple wrote:
> dax_layout_busy_page_range() is used by file systems to scan the DAX
> page-cache to unmap mapping pages from user-space and to determine if
> any pages in the given range are busy, either due to ongoing DMA or
> other get_user_pages() usage.
> 
> Currently it checks to see the file mapping is mapped into user-space
> with mapping_mapped() and returns early if not, skipping the check for
> DMA busy pages. This is wrong as pages may still be undergoing DMA
> access even if they have subsequently been unmapped from
> user-space. Fix this by dropping the check for mapping_mapped().
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> Suggested-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
diff mbox series

Patch

diff --git a/fs/dax.c b/fs/dax.c
index 21b4740..5133568 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -690,7 +690,7 @@  struct page *dax_layout_busy_page_range(struct address_space *mapping,
 	if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
 		return NULL;
 
-	if (!dax_mapping(mapping) || !mapping_mapped(mapping))
+	if (!dax_mapping(mapping))
 		return NULL;
 
 	/* If end == LLONG_MAX, all pages from start to till end of file */