tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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Merge tag 'trace-ringbuffer-v6.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ring-buffer fix from Steven Rostedt:

- Do not allow mmapped ring buffer to be split

When the ring buffer VMA is split by a partial munmap or a MAP_FIXED,
the kernel calls vm_ops->close() on each portion. This causes the
ring_buffer_unmap() to be called multiple times. This causes
subsequent calls to return -ENODEV and triggers a warning.

There's no reason to allow user space to split up memory mapping of
the ring buffer. Have it return -EINVAL when that happens.

* tag 'trace-ringbuffer-v6.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Fix WARN_ON in tracing_buffers_mmap_close for split VMAs

Linus Torvalds 4941a177 9eb220ed

+10
+10
kernel/trace/trace.c
··· 8781 8781 put_snapshot_map(iter->tr); 8782 8782 } 8783 8783 8784 + static int tracing_buffers_may_split(struct vm_area_struct *vma, unsigned long addr) 8785 + { 8786 + /* 8787 + * Trace buffer mappings require the complete buffer including 8788 + * the meta page. Partial mappings are not supported. 8789 + */ 8790 + return -EINVAL; 8791 + } 8792 + 8784 8793 static const struct vm_operations_struct tracing_buffers_vmops = { 8785 8794 .close = tracing_buffers_mmap_close, 8795 + .may_split = tracing_buffers_may_split, 8786 8796 }; 8787 8797 8788 8798 static int tracing_buffers_mmap(struct file *filp, struct vm_area_struct *vma)