The patch titled
Subject: hugetlb: revert use of page_cache_next_miss()
has been added to the -mm mm-unstable branch. Its filename is
hugetlb-revert-use-of-page_cache_next_miss.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlb-revert-use-of-page_cache_next_miss.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: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Subject: hugetlb: revert use of page_cache_next_miss()
Date: Wed, 21 Jun 2023 14:24:03 -0700
Ackerley Tng reported an issue with hugetlbfs fallocate as noted in the
Closes tag. The issue showed up after the conversion of hugetlb page
cache lookup code to use page_cache_next_miss. User visible effects are:
- hugetlbfs fallocate incorrectly returns -EEXIST if pages are presnet
in the file.
- hugetlb pages will not be included in core dumps if they need to be
brought in via GUP.
- userfaultfd UFFDIO_COPY will not notice pages already present in the
cache. It may try to allocate a new page and potentially return
ENOMEM as opposed to EEXIST.
Revert the use page_cache_next_miss() in hugetlb code.
IMPORTANT NOTE FOR STABLE BACKPORTS:
This patch will apply cleanly to v6.3. However, due to the change of
filemap_get_folio() return values, it will not function correctly. This
patch must be modified for stable backports.
Link: https://lkml.kernel.org/r/20230621212403.174710-2-mike.kravetz@xxxxxxxxxx
Fixes: d0ce0e47b323 ("mm/hugetlb: convert hugetlb fault paths to use alloc_hugetlb_folio()")
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reported-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-mm/cover.1683069252.git.ackerleytng@xxxxxxxxxx
Cc: Erdem Aktas <erdemaktas@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: kernel test robot <oliver.sang@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Reviewed-by Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Cc: Vishal Annapurve <vannapurve@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 8 +++-----
mm/hugetlb.c | 11 +++++------
2 files changed, 8 insertions(+), 11 deletions(-)
--- a/fs/hugetlbfs/inode.c~hugetlb-revert-use-of-page_cache_next_miss
+++ a/fs/hugetlbfs/inode.c
@@ -821,7 +821,6 @@ static long hugetlbfs_fallocate(struct f
*/
struct folio *folio;
unsigned long addr;
- bool present;
cond_resched();
@@ -842,10 +841,9 @@ static long hugetlbfs_fallocate(struct f
mutex_lock(&hugetlb_fault_mutex_table[hash]);
/* See if already present in mapping to avoid alloc/free */
- rcu_read_lock();
- present = page_cache_next_miss(mapping, index, 1) != index;
- rcu_read_unlock();
- if (present) {
+ folio = filemap_get_folio(mapping, index);
+ if (!IS_ERR(folio)) {
+ folio_put(folio);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
continue;
}
--- a/mm/hugetlb.c~hugetlb-revert-use-of-page_cache_next_miss
+++ a/mm/hugetlb.c
@@ -5728,13 +5728,12 @@ static bool hugetlbfs_pagecache_present(
{
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t idx = vma_hugecache_offset(h, vma, address);
- bool present;
+ struct folio *folio;
- rcu_read_lock();
- present = page_cache_next_miss(mapping, idx, 1) != idx;
- rcu_read_unlock();
-
- return present;
+ folio = filemap_get_folio(mapping, idx);
+ if (!IS_ERR(folio))
+ folio_put(folio);
+ return folio != NULL;
}
int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping,
_
Patches currently in -mm which might be from mike.kravetz@xxxxxxxxxx are
revert-page-cache-fix-page_cache_next-prev_miss-off-by-one.patch
hugetlb-revert-use-of-page_cache_next_miss.patch
