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Suren Baghdasaryan
a273559e9e
lib/alloc_tag: fix RCU imbalance in pgalloc_tag_get()
put_page_tag_ref() should be called only when get_page_tag_ref() returns a valid reference because only in that case get_page_tag_ref() enters RCU read section while put_page_tag_ref() will call rcu_read_unlock() even if the provided reference is NULL. Fix pgalloc_tag_get() which does not follow this rule causing RCU imbalance. Add a warning in put_page_tag_ref() to catch any future mistakes. Link: https://lkml.kernel.org/r/20240601233840.617458-1-surenb@google.com Fixes: cc92eba1c88b ("mm: fix non-compound multi-order memory accounting in __free_pages") Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202405271029.6d2f9c4c-lkp@intel.com Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Kees Cook <keescook@chromium.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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 reStructuredText 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.
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