2023-01-21 06:59:56

by Christoph Hellwig

[permalink] [raw]
Subject: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio

Instead of returning NULL for all errors, distinguish between:

- no entry found and not asked to allocated (-ENOENT)
- failed to allocate memory (-ENOMEM)
- would block (-EAGAIN)

so that callers don't have to guess the error based on the passed
in flags.

Also pass through the error through the direct callers:
filemap_get_folio, filemap_lock_folio filemap_grab_folio
and filemap_get_incore_folio.

Signed-off-by: Christoph Hellwig <[email protected]>
---
fs/afs/dir.c | 10 +++++-----
fs/afs/dir_edit.c | 2 +-
fs/afs/write.c | 4 ++--
fs/btrfs/disk-io.c | 2 +-
fs/ext4/inode.c | 2 +-
fs/ext4/move_extent.c | 8 ++++----
fs/hugetlbfs/inode.c | 2 +-
fs/iomap/buffered-io.c | 15 ++-------------
fs/netfs/buffered_read.c | 4 ++--
fs/nilfs2/page.c | 6 +++---
include/linux/pagemap.h | 11 ++++++-----
mm/filemap.c | 14 ++++++++------
mm/folio-compat.c | 2 +-
mm/huge_memory.c | 2 +-
mm/memcontrol.c | 2 +-
mm/mincore.c | 2 +-
mm/shmem.c | 4 ++--
mm/swap_state.c | 15 ++++++++-------
mm/swapfile.c | 4 ++--
mm/truncate.c | 15 ++++++++-------
20 files changed, 60 insertions(+), 66 deletions(-)

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 82690d1dd49a02..f92b9e62d567b9 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -319,16 +319,16 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
struct folio *folio;

folio = filemap_get_folio(mapping, i);
- if (!folio) {
+ if (IS_ERR(folio)) {
if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
afs_stat_v(dvnode, n_inval);
-
- ret = -ENOMEM;
folio = __filemap_get_folio(mapping,
i, FGP_LOCK | FGP_CREAT,
mapping->gfp_mask);
- if (!folio)
+ if (IS_ERR(folio)) {
+ ret = PTR_ERR(folio);
goto error;
+ }
folio_attach_private(folio, (void *)1);
folio_unlock(folio);
}
@@ -524,7 +524,7 @@ static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
*/
folio = __filemap_get_folio(dir->i_mapping, ctx->pos / PAGE_SIZE,
FGP_ACCESSED, 0);
- if (!folio) {
+ if (IS_ERR(folio)) {
ret = afs_bad(dvnode, afs_file_error_dir_missing_page);
break;
}
diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c
index 0ab7752d1b758e..f0eddccbdd9541 100644
--- a/fs/afs/dir_edit.c
+++ b/fs/afs/dir_edit.c
@@ -115,7 +115,7 @@ static struct folio *afs_dir_get_folio(struct afs_vnode *vnode, pgoff_t index)
folio = __filemap_get_folio(mapping, index,
FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
mapping->gfp_mask);
- if (!folio)
+ if (IS_ERR(folio))
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
else if (folio && !folio_test_private(folio))
folio_attach_private(folio, (void *)1);
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 2d3b08b7406ca7..cf1eb0d122c275 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -232,7 +232,7 @@ static void afs_kill_pages(struct address_space *mapping,
_debug("kill %lx (to %lx)", index, last);

folio = filemap_get_folio(mapping, index);
- if (!folio) {
+ if (IS_ERR(folio)) {
next = index + 1;
continue;
}
@@ -270,7 +270,7 @@ static void afs_redirty_pages(struct writeback_control *wbc,
_debug("redirty %llx @%llx", len, start);

folio = filemap_get_folio(mapping, index);
- if (!folio) {
+ if (IS_ERR(folio)) {
next = index + 1;
continue;
}
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 27abe8fdfd92b3..e888abee119fd6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4037,7 +4037,7 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)

folio = filemap_get_folio(device->bdev->bd_inode->i_mapping,
bytenr >> PAGE_SHIFT);
- if (!folio) {
+ if (IS_ERR(folio)) {
errors++;
if (i == 0)
primary_failed = true;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0f6f24bb8e8fba..b4c65e6aa360d2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5391,7 +5391,7 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
while (1) {
struct folio *folio = filemap_lock_folio(inode->i_mapping,
inode->i_size >> PAGE_SHIFT);
- if (!folio)
+ if (IS_ERR(folio))
return;
ret = __ext4_journalled_invalidate_folio(folio, offset,
folio_size(folio) - offset);
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 2de9829aed63bf..7bf6d069199cbb 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -141,18 +141,18 @@ mext_folio_double_lock(struct inode *inode1, struct inode *inode2,
flags = memalloc_nofs_save();
folio[0] = __filemap_get_folio(mapping[0], index1, fgp_flags,
mapping_gfp_mask(mapping[0]));
- if (!folio[0]) {
+ if (IS_ERR(folio[0])) {
memalloc_nofs_restore(flags);
- return -ENOMEM;
+ return PTR_ERR(folio[0]);
}

folio[1] = __filemap_get_folio(mapping[1], index2, fgp_flags,
mapping_gfp_mask(mapping[1]));
memalloc_nofs_restore(flags);
- if (!folio[1]) {
+ if (IS_ERR(folio[1])) {
folio_unlock(folio[0]);
folio_put(folio[0]);
- return -ENOMEM;
+ return PTR_ERR(folio[1]);
}
/*
* __filemap_get_folio() may not wait on folio's writeback if
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index fb810664448787..6cac1b92520af1 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -697,7 +697,7 @@ static void hugetlbfs_zero_partial_page(struct hstate *h,
struct folio *folio;

folio = filemap_lock_folio(mapping, idx);
- if (!folio)
+ if (IS_ERR(folio))
return;

start = start & ~huge_page_mask(h);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index d3c300563eb8ff..94a4d2e66ac66d 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -468,19 +468,12 @@ EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos)
{
unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
- struct folio *folio;

if (iter->flags & IOMAP_NOWAIT)
fgp |= FGP_NOWAIT;

- folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
+ return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
fgp, mapping_gfp_mask(iter->inode->i_mapping));
- if (folio)
- return folio;
-
- if (iter->flags & IOMAP_NOWAIT)
- return ERR_PTR(-EAGAIN);
- return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL_GPL(iomap_get_folio);

@@ -653,10 +646,6 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
if (!mapping_large_folio_support(iter->inode->i_mapping))
len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));

- folio = __iomap_get_folio(iter, pos, len);
- if (IS_ERR(folio))
- return PTR_ERR(folio);
-
/*
* Now we have a locked folio, before we do anything with it we need to
* check that the iomap we have cached is not stale. The inode extent
@@ -911,7 +900,7 @@ static int iomap_write_delalloc_scan(struct inode *inode,
/* grab locked page */
folio = filemap_lock_folio(inode->i_mapping,
start_byte >> PAGE_SHIFT);
- if (!folio) {
+ if (IS_ERR(folio)) {
start_byte = ALIGN_DOWN(start_byte, PAGE_SIZE) +
PAGE_SIZE;
continue;
diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index 7679a68e819307..209726a9cfdb9c 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -350,8 +350,8 @@ int netfs_write_begin(struct netfs_inode *ctx,
retry:
folio = __filemap_get_folio(mapping, index, fgp_flags,
mapping_gfp_mask(mapping));
- if (!folio)
- return -ENOMEM;
+ if (IS_ERR(folio))
+ return PTR_ERR(folio);

if (ctx->ops->check_write_begin) {
/* Allow the netfs (eg. ceph) to flush conflicts. */
diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index 41ccd43cd9797f..5cf30827f244c4 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -259,10 +259,10 @@ int nilfs_copy_dirty_pages(struct address_space *dmap,
NILFS_PAGE_BUG(&folio->page, "inconsistent dirty state");

dfolio = filemap_grab_folio(dmap, folio->index);
- if (unlikely(!dfolio)) {
+ if (unlikely(IS_ERR(dfolio))) {
/* No empty page is added to the page cache */
- err = -ENOMEM;
folio_unlock(folio);
+ err = PTR_ERR(dfolio);
break;
}
if (unlikely(!folio_buffers(folio)))
@@ -311,7 +311,7 @@ void nilfs_copy_back_pages(struct address_space *dmap,

folio_lock(folio);
dfolio = filemap_lock_folio(dmap, index);
- if (dfolio) {
+ if (!IS_ERR(dfolio)) {
/* overwrite existing folio in the destination cache */
WARN_ON(folio_test_dirty(dfolio));
nilfs_copy_page(&dfolio->page, &folio->page, 0);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e2208ee36966ea..6e07ba2ef18327 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -520,7 +520,8 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
* Looks up the page cache entry at @mapping & @index. If a folio is
* present, it is returned with an increased refcount.
*
- * Otherwise, %NULL is returned.
+ * Return: A folio or ERR_PTR(-ENOENT) if there is no folio in the cache for
+ * this index. Will not return a shadow, swap or DAX entry.
*/
static inline struct folio *filemap_get_folio(struct address_space *mapping,
pgoff_t index)
@@ -537,8 +538,8 @@ static inline struct folio *filemap_get_folio(struct address_space *mapping,
* present, it is returned locked with an increased refcount.
*
* Context: May sleep.
- * Return: A folio or %NULL if there is no folio in the cache for this
- * index. Will not return a shadow, swap or DAX entry.
+ * Return: A folio or ERR_PTR(-ENOENT) if there is no folio in the cache for
+ * this index. Will not return a shadow, swap or DAX entry.
*/
static inline struct folio *filemap_lock_folio(struct address_space *mapping,
pgoff_t index)
@@ -555,8 +556,8 @@ static inline struct folio *filemap_lock_folio(struct address_space *mapping,
* a new folio is created. The folio is locked, marked as accessed, and
* returned.
*
- * Return: A found or created folio. NULL if no folio is found and failed to
- * create a folio.
+ * Return: A found or created folio. ERR_PTR(-ENOMEM) if no folio is found
+ * and failed to create a folio.
*/
static inline struct folio *filemap_grab_folio(struct address_space *mapping,
pgoff_t index)
diff --git a/mm/filemap.c b/mm/filemap.c
index 35baadd130795c..4037a132f7adcc 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1905,7 +1905,7 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
*
* If there is a page cache page, it is returned with an increased refcount.
*
- * Return: The found folio or %NULL otherwise.
+ * Return: The found folio or an ERR_PTR() otherwise.
*/
struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
int fgp_flags, gfp_t gfp)
@@ -1923,7 +1923,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
if (fgp_flags & FGP_NOWAIT) {
if (!folio_trylock(folio)) {
folio_put(folio);
- return NULL;
+ return ERR_PTR(-EAGAIN);
}
} else {
folio_lock(folio);
@@ -1962,7 +1962,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,

folio = filemap_alloc_folio(gfp, 0);
if (!folio)
- return NULL;
+ return ERR_PTR(-ENOMEM);

if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
fgp_flags |= FGP_LOCK;
@@ -1987,6 +1987,8 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
folio_unlock(folio);
}

+ if (!folio)
+ return ERR_PTR(-ENOENT);
return folio;
}
EXPORT_SYMBOL(__filemap_get_folio);
@@ -3126,7 +3128,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
* Do we have something in the page cache already?
*/
folio = filemap_get_folio(mapping, index);
- if (likely(folio)) {
+ if (likely(!IS_ERR(folio))) {
/*
* We found the page, so try async readahead before waiting for
* the lock.
@@ -3155,7 +3157,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
folio = __filemap_get_folio(mapping, index,
FGP_CREAT|FGP_FOR_MMAP,
vmf->gfp_mask);
- if (!folio) {
+ if (IS_ERR(folio)) {
if (fpin)
goto out_retry;
filemap_invalidate_unlock_shared(mapping);
@@ -3506,7 +3508,7 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
filler = mapping->a_ops->read_folio;
repeat:
folio = filemap_get_folio(mapping, index);
- if (!folio) {
+ if (IS_ERR(folio)) {
folio = filemap_alloc_folio(gfp, 0);
if (!folio)
return ERR_PTR(-ENOMEM);
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index f3841b4977b68e..4cd173336d8589 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -97,7 +97,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
struct folio *folio;

folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
- if (!folio)
+ if (IS_ERR(folio))
return NULL;
return folio_file_page(folio, index);
}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a2830019aaa017..b0c9170632e37c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3103,7 +3103,7 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
struct folio *folio = filemap_get_folio(mapping, index);

nr_pages = 1;
- if (!folio)
+ if (IS_ERR(folio))
continue;

if (!folio_test_large(folio))
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 17335459d8dc72..7ecebdd2c23391 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5689,7 +5689,7 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
/* shmem/tmpfs may report page out on swap: account for that too. */
index = linear_page_index(vma, addr);
folio = filemap_get_incore_folio(vma->vm_file->f_mapping, index);
- if (!folio)
+ if (IS_ERR(folio))
return NULL;
return folio_file_page(folio, index);
}
diff --git a/mm/mincore.c b/mm/mincore.c
index cd69b9db008126..5437e584b208bf 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -61,7 +61,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
* tmpfs's .fault). So swapped out tmpfs mappings are tested here.
*/
folio = filemap_get_incore_folio(mapping, index);
- if (folio) {
+ if (!IS_ERR(folio)) {
present = folio_test_uptodate(folio);
folio_put(folio);
}
diff --git a/mm/shmem.c b/mm/shmem.c
index 23d5cf8182cb1f..8589ab4abd2b11 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -603,7 +603,7 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,

index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
folio = filemap_get_folio(inode->i_mapping, index);
- if (!folio)
+ if (IS_ERR(folio))
goto drop;

/* No huge page at the end of the file: nothing to split */
@@ -3187,7 +3187,7 @@ static const char *shmem_get_link(struct dentry *dentry,

if (!dentry) {
folio = filemap_get_folio(inode->i_mapping, 0);
- if (!folio)
+ if (IS_ERR(folio))
return ERR_PTR(-ECHILD);
if (PageHWPoison(folio_page(folio, 0)) ||
!folio_test_uptodate(folio)) {
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 92234f4b51d29a..c7160070b9daa9 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -336,7 +336,7 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
struct folio *folio;

folio = filemap_get_folio(swap_address_space(entry), swp_offset(entry));
- if (folio) {
+ if (!IS_ERR(folio)) {
bool vma_ra = swap_use_vma_readahead();
bool readahead;

@@ -366,6 +366,8 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
if (!vma || !vma_ra)
atomic_inc(&swapin_readahead_hits);
}
+ } else {
+ folio = NULL;
}

return folio;
@@ -389,22 +391,21 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping,
struct folio *folio = filemap_get_entry(mapping, index);

if (!xa_is_value(folio))
- goto out;
+ return folio;
if (!shmem_mapping(mapping))
- return NULL;
+ return ERR_PTR(-ENOENT);

swp = radix_to_swp_entry(folio);
/* There might be swapin error entries in shmem mapping. */
if (non_swap_entry(swp))
- return NULL;
+ return ERR_PTR(-ENOENT);
/* Prevent swapoff from happening to us */
si = get_swap_device(swp);
if (!si)
- return NULL;
+ return ERR_PTR(-ENOENT);
index = swp_offset(swp);
folio = filemap_get_folio(swap_address_space(swp), index);
put_swap_device(si);
-out:
return folio;
}

@@ -431,7 +432,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
folio = filemap_get_folio(swap_address_space(entry),
swp_offset(entry));
put_swap_device(si);
- if (folio)
+ if (!IS_ERR(folio))
return folio_file_page(folio, swp_offset(entry));

/*
diff --git a/mm/swapfile.c b/mm/swapfile.c
index a5729273480e07..a128b61b6b8c91 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -136,7 +136,7 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si,
int ret = 0;

folio = filemap_get_folio(swap_address_space(entry), offset);
- if (!folio)
+ if (IS_ERR(folio))
return 0;
/*
* When this function is called from scan_swap_map_slots() and it's
@@ -2096,7 +2096,7 @@ static int try_to_unuse(unsigned int type)

entry = swp_entry(type, i);
folio = filemap_get_folio(swap_address_space(entry), i);
- if (!folio)
+ if (IS_ERR(folio))
continue;

/*
diff --git a/mm/truncate.c b/mm/truncate.c
index 7b4ea4c4a46b20..86de31ed4d3238 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -375,7 +375,7 @@ void truncate_inode_pages_range(struct address_space *mapping,

same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
- if (folio) {
+ if (!IS_ERR(folio)) {
same_folio = lend < folio_pos(folio) + folio_size(folio);
if (!truncate_inode_partial_folio(folio, lstart, lend)) {
start = folio->index + folio_nr_pages(folio);
@@ -387,14 +387,15 @@ void truncate_inode_pages_range(struct address_space *mapping,
folio = NULL;
}

- if (!same_folio)
+ if (!same_folio) {
folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
FGP_LOCK, 0);
- if (folio) {
- if (!truncate_inode_partial_folio(folio, lstart, lend))
- end = folio->index;
- folio_unlock(folio);
- folio_put(folio);
+ if (!IS_ERR(folio)) {
+ if (!truncate_inode_partial_folio(folio, lstart, lend))
+ end = folio->index;
+ folio_unlock(folio);
+ folio_put(folio);
+ }
}

index = start;
--
2.39.0


2023-01-21 11:54:28

by kernel test robot

[permalink] [raw]
Subject: Re: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio

Hi Christoph,

I love your patch! Perhaps something to improve:

[auto build test WARNING on next-20230120]
[cannot apply to akpm-mm/mm-everything tytso-ext4/dev kdave/for-next xfs-linux/for-next konis-nilfs2/upstream linus/master v6.2-rc4 v6.2-rc3 v6.2-rc2 v6.2-rc4]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Christoph-Hellwig/mm-make-mapping_get_entry-available-outside-of-filemap-c/20230121-155847
patch link: https://lore.kernel.org/r/20230121065755.1140136-8-hch%40lst.de
patch subject: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio
config: riscv-randconfig-r013-20230119 (https://download.01.org/0day-ci/archive/20230121/[email protected]/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 4196ca3278f78c6e19246e54ab0ecb364e37d66a)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install riscv cross compiling tool for clang build
# apt-get install binutils-riscv-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/3c8a98fd03b82ace84668b3f8bb48d48e9f34af2
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Christoph-Hellwig/mm-make-mapping_get_entry-available-outside-of-filemap-c/20230121-155847
git checkout 3c8a98fd03b82ace84668b3f8bb48d48e9f34af2
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash fs/iomap/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>

All warnings (new ones prefixed by >>):

>> fs/iomap/buffered-io.c:669:28: warning: variable 'folio' is uninitialized when used here [-Wuninitialized]
if (pos + len > folio_pos(folio) + folio_size(folio))
^~~~~
fs/iomap/buffered-io.c:636:21: note: initialize the variable 'folio' to silence this warning
struct folio *folio;
^
= NULL
fs/iomap/buffered-io.c:598:22: warning: unused function '__iomap_get_folio' [-Wunused-function]
static struct folio *__iomap_get_folio(struct iomap_iter *iter, loff_t pos,
^
2 warnings generated.


vim +/folio +669 fs/iomap/buffered-io.c

69f4a26c1e0c7c Gao Xiang 2021-08-03 630
d7b64041164ca1 Dave Chinner 2022-11-29 631 static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
bc6123a84a71b5 Matthew Wilcox (Oracle 2021-05-02 632) size_t len, struct folio **foliop)
afc51aaa22f26c Darrick J. Wong 2019-07-15 633 {
471859f57d4253 Andreas Gruenbacher 2023-01-15 634 const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
fad0a1ab34f777 Christoph Hellwig 2021-08-10 635 const struct iomap *srcmap = iomap_iter_srcmap(iter);
d1bd0b4ebfe052 Matthew Wilcox (Oracle 2021-11-03 636) struct folio *folio;
afc51aaa22f26c Darrick J. Wong 2019-07-15 637 int status = 0;
afc51aaa22f26c Darrick J. Wong 2019-07-15 638
1b5c1e36dc0e0f Christoph Hellwig 2021-08-10 639 BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
1b5c1e36dc0e0f Christoph Hellwig 2021-08-10 640 if (srcmap != &iter->iomap)
c039b997927263 Goldwyn Rodrigues 2019-10-18 641 BUG_ON(pos + len > srcmap->offset + srcmap->length);
afc51aaa22f26c Darrick J. Wong 2019-07-15 642
afc51aaa22f26c Darrick J. Wong 2019-07-15 643 if (fatal_signal_pending(current))
afc51aaa22f26c Darrick J. Wong 2019-07-15 644 return -EINTR;
afc51aaa22f26c Darrick J. Wong 2019-07-15 645
d454ab82bc7f4a Matthew Wilcox (Oracle 2021-12-09 646) if (!mapping_large_folio_support(iter->inode->i_mapping))
d454ab82bc7f4a Matthew Wilcox (Oracle 2021-12-09 647) len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
d454ab82bc7f4a Matthew Wilcox (Oracle 2021-12-09 648)
d7b64041164ca1 Dave Chinner 2022-11-29 649 /*
d7b64041164ca1 Dave Chinner 2022-11-29 650 * Now we have a locked folio, before we do anything with it we need to
d7b64041164ca1 Dave Chinner 2022-11-29 651 * check that the iomap we have cached is not stale. The inode extent
d7b64041164ca1 Dave Chinner 2022-11-29 652 * mapping can change due to concurrent IO in flight (e.g.
d7b64041164ca1 Dave Chinner 2022-11-29 653 * IOMAP_UNWRITTEN state can change and memory reclaim could have
d7b64041164ca1 Dave Chinner 2022-11-29 654 * reclaimed a previously partially written page at this index after IO
d7b64041164ca1 Dave Chinner 2022-11-29 655 * completion before this write reaches this file offset) and hence we
d7b64041164ca1 Dave Chinner 2022-11-29 656 * could do the wrong thing here (zero a page range incorrectly or fail
d7b64041164ca1 Dave Chinner 2022-11-29 657 * to zero) and corrupt data.
d7b64041164ca1 Dave Chinner 2022-11-29 658 */
471859f57d4253 Andreas Gruenbacher 2023-01-15 659 if (folio_ops && folio_ops->iomap_valid) {
471859f57d4253 Andreas Gruenbacher 2023-01-15 660 bool iomap_valid = folio_ops->iomap_valid(iter->inode,
d7b64041164ca1 Dave Chinner 2022-11-29 661 &iter->iomap);
d7b64041164ca1 Dave Chinner 2022-11-29 662 if (!iomap_valid) {
d7b64041164ca1 Dave Chinner 2022-11-29 663 iter->iomap.flags |= IOMAP_F_STALE;
d7b64041164ca1 Dave Chinner 2022-11-29 664 status = 0;
d7b64041164ca1 Dave Chinner 2022-11-29 665 goto out_unlock;
d7b64041164ca1 Dave Chinner 2022-11-29 666 }
d7b64041164ca1 Dave Chinner 2022-11-29 667 }
d7b64041164ca1 Dave Chinner 2022-11-29 668
d454ab82bc7f4a Matthew Wilcox (Oracle 2021-12-09 @669) if (pos + len > folio_pos(folio) + folio_size(folio))
d454ab82bc7f4a Matthew Wilcox (Oracle 2021-12-09 670) len = folio_pos(folio) + folio_size(folio) - pos;
afc51aaa22f26c Darrick J. Wong 2019-07-15 671
c039b997927263 Goldwyn Rodrigues 2019-10-18 672 if (srcmap->type == IOMAP_INLINE)
bc6123a84a71b5 Matthew Wilcox (Oracle 2021-05-02 673) status = iomap_write_begin_inline(iter, folio);
1b5c1e36dc0e0f Christoph Hellwig 2021-08-10 674 else if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
d1bd0b4ebfe052 Matthew Wilcox (Oracle 2021-11-03 675) status = __block_write_begin_int(folio, pos, len, NULL, srcmap);
afc51aaa22f26c Darrick J. Wong 2019-07-15 676 else
bc6123a84a71b5 Matthew Wilcox (Oracle 2021-05-02 677) status = __iomap_write_begin(iter, pos, len, folio);
afc51aaa22f26c Darrick J. Wong 2019-07-15 678
afc51aaa22f26c Darrick J. Wong 2019-07-15 679 if (unlikely(status))
afc51aaa22f26c Darrick J. Wong 2019-07-15 680 goto out_unlock;
afc51aaa22f26c Darrick J. Wong 2019-07-15 681
bc6123a84a71b5 Matthew Wilcox (Oracle 2021-05-02 682) *foliop = folio;
afc51aaa22f26c Darrick J. Wong 2019-07-15 683 return 0;
afc51aaa22f26c Darrick J. Wong 2019-07-15 684
afc51aaa22f26c Darrick J. Wong 2019-07-15 685 out_unlock:
7a70a5085ed028 Andreas Gruenbacher 2023-01-15 686 __iomap_put_folio(iter, pos, 0, folio);
1b5c1e36dc0e0f Christoph Hellwig 2021-08-10 687 iomap_write_failed(iter->inode, pos, len);
afc51aaa22f26c Darrick J. Wong 2019-07-15 688
afc51aaa22f26c Darrick J. Wong 2019-07-15 689 return status;
afc51aaa22f26c Darrick J. Wong 2019-07-15 690 }
afc51aaa22f26c Darrick J. Wong 2019-07-15 691

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

2023-01-21 14:33:02

by Christoph Hellwig

[permalink] [raw]
Subject: Re: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio

On Sat, Jan 21, 2023 at 07:52:54PM +0800, kernel test robot wrote:
> Hi Christoph,
>
> I love your patch! Perhaps something to improve:

And I don't love all this hugging when something doesn't work. It feels
passive aggressive.

That being said, in this case the error is becaue the series is against
linux-next, so applying it to mainline won't work.