The patch below does not apply to the 6.3-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.3.y git checkout FETCH_HEAD git cherry-pick -x fd4aed8d985a3236d0877ff6d0c80ad39d4ce81a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023070420-fraction-such-da8d@gregkh' --subject-prefix 'PATCH 6.3.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fd4aed8d985a3236d0877ff6d0c80ad39d4ce81a Mon Sep 17 00:00:00 2001 From: Mike Kravetz mike.kravetz@oracle.com Date: Wed, 21 Jun 2023 14:24:03 -0700 Subject: [PATCH] hugetlb: revert use of page_cache_next_miss()

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.

[dan.carpenter@linaro.org: fix hugetlbfs_pagecache_present()] Link: https://lkml.kernel.org/r/efa86091-6a2c-4064-8f55-9b44e1313015@moroto.mounta... Link: https://lkml.kernel.org/r/20230621212403.174710-2-mike.kravetz@oracle.com Fixes: d0ce0e47b323 ("mm/hugetlb: convert hugetlb fault paths to use alloc_hugetlb_folio()") Signed-off-by: Mike Kravetz mike.kravetz@oracle.com Signed-off-by: Dan Carpenter dan.carpenter@linaro.org Reported-by: Ackerley Tng ackerleytng@google.com Closes: https://lore.kernel.org/linux-mm/cover.1683069252.git.ackerleytng@google.com Reviewed-by: Sidhartha Kumar sidhartha.kumar@oracle.com Cc: Erdem Aktas erdemaktas@google.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Matthew Wilcox willy@infradead.org Cc: Muchun Song songmuchun@bytedance.com Cc: Vishal Annapurve vannapurve@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 90361a922cec..7b17ccfa039d 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -821,7 +821,6 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset, */ struct folio *folio; unsigned long addr; - bool present;

cond_resched();

@@ -842,10 +841,9 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset, 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; } diff --git a/mm/hugetlb.c b/mm/hugetlb.c index d76574425da3..bce28cca73a1 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5728,13 +5728,13 @@ static bool hugetlbfs_pagecache_present(struct hstate *h, { struct address_space *mapping = vma->vm_file->f_mapping; pgoff_t idx = vma_hugecache_offset(h, vma, address); - bool present; - - rcu_read_lock(); - present = page_cache_next_miss(mapping, idx, 1) != idx; - rcu_read_unlock(); + struct folio *folio;

- return present; + folio = filemap_get_folio(mapping, idx); + if (IS_ERR(folio)) + return false; + folio_put(folio); + return true; }

int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping,