The quilt patch titled
Subject: dax: check for data cache aliasing at runtime
has been removed from the -mm tree. Its filename was
dax-check-for-data-cache-aliasing-at-runtime.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Subject: dax: check for data cache aliasing at runtime
Date: Thu, 15 Feb 2024 09:46:31 -0500
Replace the following fs/Kconfig:FS_DAX dependency:
depends on !(ARM || MIPS || SPARC)
By a runtime check within alloc_dax(). This runtime check returns
ERR_PTR(-EOPNOTSUPP) if the @ops parameter is non-NULL (which means
the kernel is using an aliased mapping) on an architecture which
has data cache aliasing.
Change the return value from NULL to PTR_ERR(-EOPNOTSUPP) for
CONFIG_DAX=n for consistency.
This is done in preparation for using cpu_dcache_is_aliasing() in a
following change which will properly support architectures which detect
data cache aliasing at runtime.
Link: https://lkml.kernel.org/r/20240215144633.96437-8-mathieu.desnoyers@xxxxxxxxxxxx
Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Alasdair Kergon <agk@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Michael Sclafani <dm-devel@xxxxxxxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/dax/super.c | 10 ++++++++++
fs/Kconfig | 1 -
2 files changed, 10 insertions(+), 1 deletion(-)
--- a/drivers/dax/super.c~dax-check-for-data-cache-aliasing-at-runtime
+++ a/drivers/dax/super.c
@@ -451,6 +451,16 @@ struct dax_device *alloc_dax(void *priva
dev_t devt;
int minor;
+ /*
+ * Unavailable on architectures with virtually aliased data caches,
+ * except for device-dax (NULL operations pointer), which does
+ * not use aliased mappings from the kernel.
+ */
+ if (ops && (IS_ENABLED(CONFIG_ARM) ||
+ IS_ENABLED(CONFIG_MIPS) ||
+ IS_ENABLED(CONFIG_SPARC)))
+ return ERR_PTR(-EOPNOTSUPP);
+
if (WARN_ON_ONCE(ops && !ops->zero_page_range))
return ERR_PTR(-EINVAL);
--- a/fs/Kconfig~dax-check-for-data-cache-aliasing-at-runtime
+++ a/fs/Kconfig
@@ -60,7 +60,6 @@ endif # BLOCK
config FS_DAX
bool "File system based Direct Access (DAX) support"
depends on MMU
- depends on !(ARM || MIPS || SPARC)
depends on ZONE_DEVICE || FS_DAX_LIMITED
select FS_IOMAP
select DAX
_
Patches currently in -mm which might be from mathieu.desnoyers@xxxxxxxxxxxx are
