linux-kernel - [PATCH AUTOSEL for 4.14 095/161] fs/dax.c: release PMD lock even when there is no PMD support in DAX

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Date:   Mon, 9 Apr 2018 00:21:06 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Jan H. Schönherr <jschoenh@...zon.de>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.14 095/161] fs/dax.c: release PMD lock even when
 there is no PMD support in DAX

From: Jan H. Schönherr <jschoenh@...zon.de>

[ Upstream commit ee190ca6516bc8257e3d36187ca6f0f71a9ec477 ]

follow_pte_pmd() can theoretically return after having acquired a PMD
lock, even when DAX was not compiled with CONFIG_FS_DAX_PMD.

Release the PMD lock unconditionally.

Link: http://lkml.kernel.org/r/20180118133839.20587-1-jschoenh@amazon.de
Fixes: f729c8c9b24f ("dax: wrprotect pmd_t in dax_mapping_entry_mkclean")
Signed-off-by: Jan H. Schönherr <jschoenh@...zon.de>
Reviewed-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Matthew Wilcox <mawilcox@...rosoft.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 fs/dax.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 191306cd8b6b..ddb4981ae32e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -630,8 +630,8 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping,
 			set_pmd_at(vma->vm_mm, address, pmdp, pmd);
 			mmu_notifier_invalidate_range(vma->vm_mm, start, end);
 unlock_pmd:
-			spin_unlock(ptl);
 #endif
+			spin_unlock(ptl);
 		} else {
 			if (pfn != pte_pfn(*ptep))
 				goto unlock_pte;
-- 
2.15.1