linux-kernel - [PATCH v4 7/7] pmem: fix pmem_do_write() avoid writing to 'np' page

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Date:   Wed, 26 Jan 2022 14:11:16 -0700
From:   Jane Chu <jane.chu@...cle.com>
To:     david@...morbit.com, djwong@...nel.org, dan.j.williams@...el.com,
        hch@...radead.org, vishal.l.verma@...el.com, dave.jiang@...el.com,
        agk@...hat.com, snitzer@...hat.com, dm-devel@...hat.com,
        ira.weiny@...el.com, willy@...radead.org, vgoyal@...hat.com,
        linux-fsdevel@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org
Subject: [PATCH v4 7/7] pmem: fix pmem_do_write() avoid writing to 'np' page

Since poisoned page is marked as not-present, the first of the
two back-to-back write_pmem() calls can only be made when there
is no poison in the range, otherwise kernel Oops.

Signed-off-by: Jane Chu <jane.chu@...cle.com>
---
 drivers/nvdimm/pmem.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index f2d6b34d48de..283890084d58 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -187,10 +187,15 @@ static blk_status_t pmem_do_write(struct pmem_device *pmem,
 	 * after clear poison.
 	 */
 	flush_dcache_page(page);
-	write_pmem(pmem_addr, page, page_off, len);
-	if (unlikely(bad_pmem)) {
-		rc = pmem_clear_poison(pmem, pmem_off, len);
+	if (!bad_pmem) {
 		write_pmem(pmem_addr, page, page_off, len);
+	} else {
+		rc = pmem_clear_poison(pmem, pmem_off, len);
+		if (rc == BLK_STS_OK)
+			write_pmem(pmem_addr, page, page_off, len);
+		else
+			pr_warn("%s: failed to clear poison\n",
+				__func__);
 	}
 
 	return rc;
-- 
2.18.4