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authorLinus Torvalds <torvalds@linux-foundation.org>2022-04-20 22:07:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-04-20 22:07:53 +0300
commit906f904097359d059623ca8d3511d9f341080f2c (patch)
tree22d5345c6b93c87085042d943208d37c541b6c38 /fs
parenta6823e4e360fe975bd3da4ab156df7c74c8b07f3 (diff)
downloadlinux-906f904097359d059623ca8d3511d9f341080f2c.tar.xz
Revert "fs/pipe: use kvcalloc to allocate a pipe_buffer array"
This reverts commit 5a519c8fe4d620912385f94372fc8472fa98c662. It turns out that making the pipe almost arbitrarily large has some rather unexpected downsides. The kernel test robot reports a kernel warning that is due to pipe->max_usage now growing to the point where the iter_file_splice_write() buffer allocation can no longer be satisfied as a slab allocation, and the int nbufs = pipe->max_usage; struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), GFP_KERNEL); code sequence there will now always fail as a result. That code could be modified to use kvcalloc() too, but I feel very uncomfortable making those kinds of changes for a very niche use case that really should have other options than make these kinds of fundamental changes to pipe behavior. Maybe the CRIU process dumping should be multi-threaded, and use multiple pipes and multiple cores, rather than try to use one larger pipe to minimize splice() calls. Reported-by: kernel test robot <oliver.sang@intel.com> Link: https://lore.kernel.org/all/20220420073717.GD16310@xsang-OptiPlex-9020/ Cc: Andrei Vagin <avagin@gmail.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/pipe.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index 9648ac15164a..e140ea150bbb 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -804,7 +804,7 @@ struct pipe_inode_info *alloc_pipe_info(void)
if (too_many_pipe_buffers_hard(user_bufs) && pipe_is_unprivileged_user())
goto out_revert_acct;
- pipe->bufs = kvcalloc(pipe_bufs, sizeof(struct pipe_buffer),
+ pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
GFP_KERNEL_ACCOUNT);
if (pipe->bufs) {
@@ -849,7 +849,7 @@ void free_pipe_info(struct pipe_inode_info *pipe)
#endif
if (pipe->tmp_page)
__free_page(pipe->tmp_page);
- kvfree(pipe->bufs);
+ kfree(pipe->bufs);
kfree(pipe);
}
@@ -1264,7 +1264,8 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
if (nr_slots < n)
return -EBUSY;
- bufs = kvcalloc(nr_slots, sizeof(*bufs), GFP_KERNEL_ACCOUNT);
+ bufs = kcalloc(nr_slots, sizeof(*bufs),
+ GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
if (unlikely(!bufs))
return -ENOMEM;
@@ -1291,7 +1292,7 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
head = n;
tail = 0;
- kvfree(pipe->bufs);
+ kfree(pipe->bufs);
pipe->bufs = bufs;
pipe->ring_size = nr_slots;
if (pipe->max_usage > nr_slots)