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authorDan Williams <dan.j.williams@intel.com>2018-05-03 17:06:21 -0700
committerIngo Molnar <mingo@kernel.org>2018-05-15 08:32:42 +0200
commit60622d68227d6d71fdfba5fb39f7f3d44cdd8815 (patch)
tree345ff9c60d43d8d3720053a25f855289cd9570ff /drivers/nvdimm/pmem.c
parentbd131544aa7e318a5735cbcbad46c4a5ee6b9d42 (diff)
x86/asm/memcpy_mcsafe: Return bytes remaining
Machine check safe memory copies are currently deployed in the pmem driver whenever reading from persistent memory media, so that -EIO is returned rather than triggering a kernel panic. While this protects most pmem accesses, it is not complete in the filesystem-dax case. When filesystem-dax is enabled reads may bypass the block layer and the driver via dax_iomap_actor() and its usage of copy_to_iter(). In preparation for creating a copy_to_iter() variant that can handle machine checks, teach memcpy_mcsafe() to return the number of bytes remaining rather than -EFAULT when an exception occurs. Co-developed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: hch@lst.de Cc: linux-fsdevel@vger.kernel.org Cc: linux-nvdimm@lists.01.org Link: http://lkml.kernel.org/r/152539238119.31796.14318473522414462886.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/nvdimm/pmem.c')
-rw-r--r--drivers/nvdimm/pmem.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 9d714926ecf5..e023d6aa22b5 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -101,15 +101,15 @@ static blk_status_t read_pmem(struct page *page, unsigned int off,
void *pmem_addr, unsigned int len)
{
unsigned int chunk;
- int rc;
+ unsigned long rem;
void *mem;
while (len) {
mem = kmap_atomic(page);
chunk = min_t(unsigned int, len, PAGE_SIZE);
- rc = memcpy_mcsafe(mem + off, pmem_addr, chunk);
+ rem = memcpy_mcsafe(mem + off, pmem_addr, chunk);
kunmap_atomic(mem);
- if (rc)
+ if (rem)
return BLK_STS_IOERR;
len -= chunk;
off = 0;