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commit aaa52e340073b7f4593b3c4ddafcafa70cf838b5 upstream. Huge tmpfs testing on a shortish file mapped into a pmd-rounded extent hit shmem_evict_inode()'s WARN_ON(inode->i_blocks) followed by clear_inode()'s BUG_ON(inode->i_data.nrpages) when the file was later closed and unlinked. khugepaged's collapse_shmem() was forgetting to update mapping->nrpages on the rollback path, after it had added but then needs to undo some holes. There is indeed an irritating asymmetry between shmem_charge(), whose callers want it to increment nrpages after successfully accounting blocks, and shmem_uncharge(), when __delete_from_page_cache() already decremented nrpages itself: oh well, just add a comment on that to them both. And shmem_recalc_inode() is supposed to be called when the accounting is expected to be in balance (so it can deduce from imbalance that reclaim discarded some pages): so change shmem_charge() to update nrpages earlier (though it's rare for the difference to matter at all). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261523450.2275@eggly.anvils Fixes: 800d8c63b2e98 ("shmem: add huge pages support") Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.