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| author | Andrei Vagin <avagin@gmail.com> | 2022-03-23 16:06:17 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-23 19:00:34 -0700 |
| commit | 5a519c8fe4d620912385f94372fc8472fa98c662 (patch) | |
| tree | 5dba915ee9aca31ea35c8a0b3c92a1ff71963ad6 /fs | |
| parent | f9a40b0890658330c83c95511f9d6b396610defc (diff) | |
| download | lwn-5a519c8fe4d620912385f94372fc8472fa98c662.tar.gz lwn-5a519c8fe4d620912385f94372fc8472fa98c662.zip | |
fs/pipe: use kvcalloc to allocate a pipe_buffer array
Right now, kcalloc is used to allocate a pipe_buffer array. The size of
the pipe_buffer struct is 40 bytes. kcalloc allows allocating reliably
chunks with sizes less or equal to PAGE_ALLOC_COSTLY_ORDER (3). It
means that the maximum pipe size is 3.2MB in this case.
In CRIU, we use pipes to dump processes memory. CRIU freezes a target
process, injects a parasite code into it and then this code splices
memory into pipes. If a maximum pipe size is small, we need to do many
iterations or create many pipes.
kvcalloc attempt to allocate physically contiguous memory, but upon
failure, fall back to non-contiguous (vmalloc) allocation and so it
isn't limited by PAGE_ALLOC_COSTLY_ORDER.
The maximum pipe size for non-root users is limited by the
/proc/sys/fs/pipe-max-size sysctl that is 1MB by default, so only the
root user will be able to trigger vmalloc allocations.
Link: https://lkml.kernel.org/r/20220104171058.22580-1-avagin@gmail.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/pipe.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 2667db9506e2..ba0841b6674b 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 = kcalloc(pipe_bufs, sizeof(struct pipe_buffer), + pipe->bufs = kvcalloc(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); - kfree(pipe->bufs); + kvfree(pipe->bufs); kfree(pipe); } @@ -1264,8 +1264,7 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots) if (nr_slots < n) return -EBUSY; - bufs = kcalloc(nr_slots, sizeof(*bufs), - GFP_KERNEL_ACCOUNT | __GFP_NOWARN); + bufs = kvcalloc(nr_slots, sizeof(*bufs), GFP_KERNEL_ACCOUNT); if (unlikely(!bufs)) return -ENOMEM; @@ -1292,7 +1291,7 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots) head = n; tail = 0; - kfree(pipe->bufs); + kvfree(pipe->bufs); pipe->bufs = bufs; pipe->ring_size = nr_slots; if (pipe->max_usage > nr_slots) |