path: root/arch/s390
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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2020-02-27 12:56:42 +0100
committerVasily Gorbik <gor@linux.ibm.com>2020-03-04 11:18:03 +0100
commit582b4e55403e053d8a48ff687a05174da9cc3fb0 (patch)
treebfccd6c8badecf95646b1a322428a52435a8e53a /arch/s390
parentLinux 5.6-rc4 (diff)
s390/mm: fix panic in gup_fast on large pud
On s390 there currently is no implementation of pud_write(). That was ok as long as we had our own implementation of get_user_pages_fast() which checked for pud protection by testing the bit directly w/o using pud_write(). The other callers of pud_write() are not reachable on s390. After commit 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") we use the generic get_user_pages_fast(), which does call pud_write() in pud_access_permitted() for FOLL_WRITE access on a large pud. Without an s390 specific pud_write(), the generic version is called, which contains a BUG() statement to remind us that we don't have a proper implementation. This results in a kernel panic. Fix this by providing an implementation of pud_write(). Cc: <stable@vger.kernel.org> # 5.2+ Fixes: 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390')
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 137a3920ca36..6d7c3b7e9281 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -752,6 +752,12 @@ static inline int pmd_write(pmd_t pmd)
return (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) != 0;
+#define pud_write pud_write
+static inline int pud_write(pud_t pud)
+ return (pud_val(pud) & _REGION3_ENTRY_WRITE) != 0;
static inline int pmd_dirty(pmd_t pmd)
return (pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY) != 0;