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4a565c8069
This fixes as case in "btrfs: refactor alloc_extent_buffer() to allocate-then-attach method". We have been seeing panics in the CI for the subpage stuff recently, it happens on btrfs/187 but could potentially happen anywhere. In the subpage case, if we race with somebody else inserting the same extent buffer, the error case will end up calling detach_extent_buffer_page() on the page twice. This is done first in the bit for (int i = 0; i < attached; i++) detach_extent_buffer_page(eb, eb->pages[i]; and then again in btrfs_release_extent_buffer(). This works fine for !subpage because we're the only person who ever has ourselves on the private, and so when we do the initial detach_extent_buffer_page() we know we've completely removed it. However for subpage we could be using this page private elsewhere, so this results in a double put on the subpage, which can result in an early freeing. The fix here is to clear eb->pages[i] for everything we detach. Then anything still attached to the eb is freed in btrfs_release_extent_buffer(). Because of this change we must update btrfs_release_extent_buffer_pages() to not use num_extent_folios, because it assumes eb->folio[0] is set properly. Since this is only interested in freeing any pages we have on the extent buffer we can simply use INLINE_EXTENT_BUFFER_PAGES. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.