* + hugetlbfs-improve-read-hwpoison-hugepage.patch added to mm-unstable branch
@ 2023-07-07 21:06 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2023-07-07 21:06 UTC (permalink / raw)
To: mm-commits, willy, songmuchun, shy828301, naoya.horiguchi,
mike.kravetz, linmiaohe, jthoughton, axelrasmussen, jiaqiyan,
akpm
The patch titled
Subject: hugetlbfs: improve read HWPOISON hugepage
has been added to the -mm mm-unstable branch. Its filename is
hugetlbfs-improve-read-hwpoison-hugepage.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlbfs-improve-read-hwpoison-hugepage.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
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c) Ideally: find the original patch on the mailing list and do a
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Jiaqi Yan <jiaqiyan@google.com>
Subject: hugetlbfs: improve read HWPOISON hugepage
Date: Fri, 7 Jul 2023 20:19:03 +0000
When a hugepage contains HWPOISON pages, read() fails to read any byte of
the hugepage and returns -EIO, although many bytes in the HWPOISON
hugepage are readable.
Improve this by allowing hugetlbfs_read_iter returns as many bytes as
possible. For a requested range [offset, offset + len) that contains
HWPOISON page, return [offset, first HWPOISON page addr); the next read
attempt will fail and return -EIO.
Link: https://lkml.kernel.org/r/20230707201904.953262-4-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/hugetlbfs/inode.c | 58 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 52 insertions(+), 6 deletions(-)
--- a/fs/hugetlbfs/inode.c~hugetlbfs-improve-read-hwpoison-hugepage
+++ a/fs/hugetlbfs/inode.c
@@ -283,6 +283,42 @@ hugetlb_get_unmapped_area(struct file *f
#endif
/*
+ * Someone wants to read @bytes from a HWPOISON hugetlb @page from @offset.
+ * Returns the maximum number of bytes one can read without touching the 1st raw
+ * HWPOISON subpage.
+ *
+ * The implementation borrows the iteration logic from copy_page_to_iter*.
+ */
+static size_t adjust_range_hwpoison(struct page *page, size_t offset, size_t bytes)
+{
+ size_t n = 0;
+ size_t res = 0;
+ struct folio *folio = page_folio(page);
+
+ /* First subpage to start the loop. */
+ page += offset / PAGE_SIZE;
+ offset %= PAGE_SIZE;
+ while (1) {
+ if (is_raw_hwp_subpage(folio, page))
+ break;
+
+ /* Safe to read n bytes without touching HWPOISON subpage. */
+ n = min(bytes, (size_t)PAGE_SIZE - offset);
+ res += n;
+ bytes -= n;
+ if (!bytes || !n)
+ break;
+ offset += n;
+ if (offset == PAGE_SIZE) {
+ page++;
+ offset = 0;
+ }
+ }
+
+ return res;
+}
+
+/*
* Support for read() - Find the page attached to f_mapping and copy out the
* data. This provides functionality similar to filemap_read().
*/
@@ -300,7 +336,7 @@ static ssize_t hugetlbfs_read_iter(struc
while (iov_iter_count(to)) {
struct page *page;
- size_t nr, copied;
+ size_t nr, copied, want;
/* nr is the maximum number of bytes to copy from this page */
nr = huge_page_size(h);
@@ -328,16 +364,26 @@ static ssize_t hugetlbfs_read_iter(struc
} else {
unlock_page(page);
- if (PageHWPoison(page)) {
- put_page(page);
- retval = -EIO;
- break;
+ if (!PageHWPoison(page))
+ want = nr;
+ else {
+ /*
+ * Adjust how many bytes safe to read without
+ * touching the 1st raw HWPOISON subpage after
+ * offset.
+ */
+ want = adjust_range_hwpoison(page, offset, nr);
+ if (want == 0) {
+ put_page(page);
+ retval = -EIO;
+ break;
+ }
}
/*
* We have the page, copy it to user space buffer.
*/
- copied = copy_page_to_iter(page, offset, nr, to);
+ copied = copy_page_to_iter(page, offset, want, to);
put_page(page);
}
offset += copied;
_
Patches currently in -mm which might be from jiaqiyan@google.com are
mm-hwpoison-delete-all-entries-before-traversal-in-__folio_free_raw_hwp.patch
mm-hwpoison-check-if-a-subpage-of-a-hugetlb-folio-is-raw-hwpoison.patch
hugetlbfs-improve-read-hwpoison-hugepage.patch
selftests-mm-add-tests-for-hwpoison-hugetlbfs-read.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
* + hugetlbfs-improve-read-hwpoison-hugepage.patch added to mm-unstable branch
@ 2023-07-13 16:18 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2023-07-13 16:18 UTC (permalink / raw)
To: mm-commits, songmuchun, shy828301, naoya.horiguchi, mike.kravetz,
linmiaohe, jthoughton, jiaqiyan, akpm
The patch titled
Subject: hugetlbfs: improve read HWPOISON hugepage
has been added to the -mm mm-unstable branch. Its filename is
hugetlbfs-improve-read-hwpoison-hugepage.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlbfs-improve-read-hwpoison-hugepage.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Jiaqi Yan <jiaqiyan@google.com>
Subject: hugetlbfs: improve read HWPOISON hugepage
Date: Thu, 13 Jul 2023 00:18:32 +0000
When a hugepage contains HWPOISON pages, read() fails to read any byte of
the hugepage and returns -EIO, although many bytes in the HWPOISON
hugepage are readable.
Improve this by allowing hugetlbfs_read_iter returns as many bytes as
possible. For a requested range [offset, offset + len) that contains
HWPOISON page, return [offset, first HWPOISON page addr); the next read
attempt will fail and return -EIO.
Link: https://lkml.kernel.org/r/20230713001833.3778937-4-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/hugetlbfs/inode.c | 57 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 51 insertions(+), 6 deletions(-)
--- a/fs/hugetlbfs/inode.c~hugetlbfs-improve-read-hwpoison-hugepage
+++ a/fs/hugetlbfs/inode.c
@@ -283,6 +283,41 @@ hugetlb_get_unmapped_area(struct file *f
#endif
/*
+ * Someone wants to read @bytes from a HWPOISON hugetlb @page from @offset.
+ * Returns the maximum number of bytes one can read without touching the 1st raw
+ * HWPOISON subpage.
+ *
+ * The implementation borrows the iteration logic from copy_page_to_iter*.
+ */
+static size_t adjust_range_hwpoison(struct page *page, size_t offset, size_t bytes)
+{
+ size_t n = 0;
+ size_t res = 0;
+
+ /* First subpage to start the loop. */
+ page += offset / PAGE_SIZE;
+ offset %= PAGE_SIZE;
+ while (1) {
+ if (is_raw_hwpoison_page_in_hugepage(page))
+ break;
+
+ /* Safe to read n bytes without touching HWPOISON subpage. */
+ n = min(bytes, (size_t)PAGE_SIZE - offset);
+ res += n;
+ bytes -= n;
+ if (!bytes || !n)
+ break;
+ offset += n;
+ if (offset == PAGE_SIZE) {
+ page++;
+ offset = 0;
+ }
+ }
+
+ return res;
+}
+
+/*
* Support for read() - Find the page attached to f_mapping and copy out the
* data. This provides functionality similar to filemap_read().
*/
@@ -300,7 +335,7 @@ static ssize_t hugetlbfs_read_iter(struc
while (iov_iter_count(to)) {
struct page *page;
- size_t nr, copied;
+ size_t nr, copied, want;
/* nr is the maximum number of bytes to copy from this page */
nr = huge_page_size(h);
@@ -328,16 +363,26 @@ static ssize_t hugetlbfs_read_iter(struc
} else {
unlock_page(page);
- if (PageHWPoison(page)) {
- put_page(page);
- retval = -EIO;
- break;
+ if (!PageHWPoison(page))
+ want = nr;
+ else {
+ /*
+ * Adjust how many bytes safe to read without
+ * touching the 1st raw HWPOISON subpage after
+ * offset.
+ */
+ want = adjust_range_hwpoison(page, offset, nr);
+ if (want == 0) {
+ put_page(page);
+ retval = -EIO;
+ break;
+ }
}
/*
* We have the page, copy it to user space buffer.
*/
- copied = copy_page_to_iter(page, offset, nr, to);
+ copied = copy_page_to_iter(page, offset, want, to);
put_page(page);
}
offset += copied;
_
Patches currently in -mm which might be from jiaqiyan@google.com are
mm-hwpoison-delete-all-entries-before-traversal-in-__folio_free_raw_hwp.patch
mm-hwpoison-check-if-a-raw-page-in-a-hugetlb-folio-is-raw-hwpoison.patch
hugetlbfs-improve-read-hwpoison-hugepage.patch
selftests-mm-add-tests-for-hwpoison-hugetlbfs-read.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
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