This is a note to let you know that I've just added the patch titled
iov_iter: Introduce nofault flag to disable page faults
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iov_iter-introduce-nofault-flag-to-disable-page-faults.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Apr 29 11:07:48 AM CEST 2022
From: Anand Jain <anand.jain@xxxxxxxxxx>
Date: Fri, 15 Apr 2022 06:28:52 +0800
Subject: iov_iter: Introduce nofault flag to disable page faults
To: stable@xxxxxxxxxxxxxxx
Cc: linux-btrfs@xxxxxxxxxxxxxxx, Andreas Gruenbacher <agruenba@xxxxxxxxxx>, Anand Jain <anand.jain@xxxxxxxxxx>
Message-ID: <56bf354a8e9c5f2d3d9482c90510d4ff0890d996.1649951733.git.anand.jain@xxxxxxxxxx>
From: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
commit 3337ab08d08b1a375f88471d9c8b1cac968cb054 upstream
Introduce a new nofault flag to indicate to iov_iter_get_pages not to
fault in user pages.
This is implemented by passing the FOLL_NOFAULT flag to get_user_pages,
which causes get_user_pages to fail when it would otherwise fault in a
page. We'll use the ->nofault flag to prevent iomap_dio_rw from faulting
in pages when page faults are not allowed.
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/uio.h | 1 +
lib/iov_iter.c | 20 +++++++++++++++-----
2 files changed, 16 insertions(+), 5 deletions(-)
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -35,6 +35,7 @@ struct iov_iter_state {
struct iov_iter {
u8 iter_type;
+ bool nofault;
bool data_source;
size_t iov_offset;
size_t count;
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -514,6 +514,7 @@ void iov_iter_init(struct iov_iter *i, u
WARN_ON(direction & ~(READ | WRITE));
*i = (struct iov_iter) {
.iter_type = ITER_IOVEC,
+ .nofault = false,
.data_source = direction,
.iov = iov,
.nr_segs = nr_segs,
@@ -1529,13 +1530,17 @@ ssize_t iov_iter_get_pages(struct iov_it
return 0;
if (likely(iter_is_iovec(i))) {
+ unsigned int gup_flags = 0;
unsigned long addr;
+ if (iov_iter_rw(i) != WRITE)
+ gup_flags |= FOLL_WRITE;
+ if (i->nofault)
+ gup_flags |= FOLL_NOFAULT;
+
addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
n = DIV_ROUND_UP(len, PAGE_SIZE);
- res = get_user_pages_fast(addr, n,
- iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0,
- pages);
+ res = get_user_pages_fast(addr, n, gup_flags, pages);
if (unlikely(res <= 0))
return res;
return (res == n ? len : res * PAGE_SIZE) - *start;
@@ -1651,15 +1656,20 @@ ssize_t iov_iter_get_pages_alloc(struct
return 0;
if (likely(iter_is_iovec(i))) {
+ unsigned int gup_flags = 0;
unsigned long addr;
+ if (iov_iter_rw(i) != WRITE)
+ gup_flags |= FOLL_WRITE;
+ if (i->nofault)
+ gup_flags |= FOLL_NOFAULT;
+
addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
n = DIV_ROUND_UP(len, PAGE_SIZE);
p = get_pages_array(n);
if (!p)
return -ENOMEM;
- res = get_user_pages_fast(addr, n,
- iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p);
+ res = get_user_pages_fast(addr, n, gup_flags, p);
if (unlikely(res <= 0)) {
kvfree(p);
*pages = NULL;
Patches currently in stable-queue which might be from anand.jain@xxxxxxxxxx are
queue-5.15/gup-turn-fault_in_pages_-readable-writeable-into-fault_in_-readable-writeable.patch
queue-5.15/iov_iter-introduce-nofault-flag-to-disable-page-faults.patch
queue-5.15/gfs2-fix-mmap-page-fault-deadlocks-for-direct-i-o.patch
queue-5.15/iomap-support-partial-direct-i-o-on-user-copy-failures.patch
queue-5.15/mm-gup-make-fault_in_safe_writeable-use-fixup_user_fault.patch
queue-5.15/gfs2-add-wrapper-for-iomap_file_buffered_write.patch
queue-5.15/gup-introduce-foll_nofault-flag-to-disable-page-faults.patch
queue-5.15/iov_iter-introduce-fault_in_iov_iter_writeable.patch
queue-5.15/gfs2-fix-mmap-page-fault-deadlocks-for-buffered-i-o.patch
queue-5.15/btrfs-fallback-to-blocking-mode-when-doing-async-dio-over-multiple-extents.patch
queue-5.15/gfs2-clean-up-function-may_grant.patch
queue-5.15/btrfs-fix-deadlock-due-to-page-faults-during-direct-io-reads-and-writes.patch
queue-5.15/iov_iter-turn-iov_iter_fault_in_readable-into-fault_in_iov_iter_readable.patch
queue-5.15/gfs2-move-the-inode-glock-locking-to-gfs2_file_buffered_write.patch
queue-5.15/gfs2-introduce-flag-for-glock-holder-auto-demotion.patch
queue-5.15/iomap-fix-iomap_dio_rw-return-value-for-user-copies.patch
queue-5.15/gfs2-eliminate-ip-i_gh.patch
queue-5.15/iomap-add-done_before-argument-to-iomap_dio_rw.patch
