From: Anand Jain <anand.jain@oracle.com>
To: stable@vger.kernel.org
Cc: linux-btrfs@vger.kernel.org,
Andreas Gruenbacher <agruenba@redhat.com>,
Anand Jain <anand.jain@oracle.com>
Subject: [PATCH 13/17 stable-5.15.y] gup: Introduce FOLL_NOFAULT flag to disable page faults
Date: Sat, 2 Apr 2022 18:25:50 +0800 [thread overview]
Message-ID: <b1925ae2efbb181f76139437b1dd5129df6fdb81.1648636044.git.anand.jain@oracle.com> (raw)
In-Reply-To: <cover.1648636044.git.anand.jain@oracle.com>
From: Andreas Gruenbacher <agruenba@redhat.com>
commit 55b8fe703bc51200d4698596c90813453b35ae63 upstream
Introduce a new FOLL_NOFAULT flag that causes get_user_pages to return
-EFAULT when it would otherwise trigger a page fault. This is roughly
similar to FOLL_FAST_ONLY but available on all architectures, and less
fragile.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
include/linux/mm.h | 3 ++-
mm/gup.c | 4 +++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 90c2d7f3c7a8..04345ff97f8c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2858,7 +2858,8 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
#define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */
#define FOLL_NOWAIT 0x20 /* if a disk transfer is needed, start the IO
* and return without waiting upon it */
-#define FOLL_POPULATE 0x40 /* fault in page */
+#define FOLL_POPULATE 0x40 /* fault in pages (with FOLL_MLOCK) */
+#define FOLL_NOFAULT 0x80 /* do not fault in pages */
#define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
#define FOLL_NUMA 0x200 /* force NUMA hinting page fault */
#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
diff --git a/mm/gup.c b/mm/gup.c
index bd53a5bb715d..a4c6affe6df3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -943,6 +943,8 @@ static int faultin_page(struct vm_area_struct *vma,
/* mlock all present pages, but do not fault in new pages */
if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
return -ENOENT;
+ if (*flags & FOLL_NOFAULT)
+ return -EFAULT;
if (*flags & FOLL_WRITE)
fault_flags |= FAULT_FLAG_WRITE;
if (*flags & FOLL_REMOTE)
@@ -2868,7 +2870,7 @@ static int internal_get_user_pages_fast(unsigned long start,
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
FOLL_FORCE | FOLL_PIN | FOLL_GET |
- FOLL_FAST_ONLY)))
+ FOLL_FAST_ONLY | FOLL_NOFAULT)))
return -EINVAL;
if (gup_flags & FOLL_PIN)
--
2.33.1
next prev parent reply other threads:[~2022-04-02 10:28 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-02 10:25 [PATCH 00/17 stable-5.15.y] Fix mmap + page fault deadlocks Anand Jain
2022-04-02 10:25 ` [PATCH 01/17 stable-5.15.y] powerpc/kvm: Fix kvm_use_magic_page Anand Jain
2022-04-02 10:25 ` [PATCH 02/17 stable-5.15.y] gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable} Anand Jain
2022-04-02 10:25 ` [PATCH 03/17 stable-5.15.y] iov_iter: Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable Anand Jain
2022-04-02 10:25 ` [PATCH 04/17 stable-5.15.y] iov_iter: Introduce fault_in_iov_iter_writeable Anand Jain
2022-04-02 10:25 ` [PATCH 05/17 stable-5.15.y] gfs2: Add wrapper for iomap_file_buffered_write Anand Jain
2022-04-02 10:25 ` [PATCH 06/17 stable-5.15.y] gfs2: Clean up function may_grant Anand Jain
2022-04-02 10:25 ` [PATCH 07/17 stable-5.15.y] gfs2: Move the inode glock locking to gfs2_file_buffered_write Anand Jain
2022-04-02 10:25 ` [PATCH 08/17 stable-5.15.y] gfs2: Eliminate ip->i_gh Anand Jain
2022-04-02 10:25 ` [PATCH 09/17 stable-5.15.y] gfs2: Fix mmap + page fault deadlocks for buffered I/O Anand Jain
2022-04-02 10:25 ` [PATCH 10/17 stable-5.15.y] iomap: Fix iomap_dio_rw return value for user copies Anand Jain
2022-04-02 10:25 ` [PATCH 11/17 stable-5.15.y] iomap: Support partial direct I/O on user copy failures Anand Jain
2022-04-02 10:25 ` [PATCH 12/17 stable-5.15.y] iomap: Add done_before argument to iomap_dio_rw Anand Jain
2022-04-02 10:25 ` Anand Jain [this message]
2022-04-02 10:25 ` [PATCH 14/17 stable-5.15.y] iov_iter: Introduce nofault flag to disable page faults Anand Jain
2022-04-02 10:25 ` [PATCH 15/17 stable-5.15.y] gfs2: Fix mmap + page fault deadlocks for direct I/O Anand Jain
2022-04-02 10:25 ` [PATCH 16/17 stable-5.15.y] gfs2: Introduce flag for glock holder auto-demotion Anand Jain
2022-04-02 10:25 ` [PATCH 17/17 stable-5.15.y] btrfs: fix deadlock due to page faults during direct IO reads and writes Anand Jain
2022-04-04 9:41 ` [PATCH 00/17 stable-5.15.y] Fix mmap + page fault deadlocks Filipe Manana
2022-04-05 11:32 ` Anand Jain
2022-04-11 7:49 ` Greg KH
2022-04-12 5:14 ` Anand Jain
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