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Received: from willy by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wZwY2-0000000DDQk-3y3d; Wed, 17 Jun 2026 20:07:43 +0000 Date: Wed, 17 Jun 2026 21:07:42 +0100 From: Matthew Wilcox To: Jane Chu Cc: akpm@linux-foundation.org, jack@suse.cz, viro@zeniv.linux.org.uk, brauner@kernel.org, muchun.song@linux.dev, osalvador@suse.de, david@kernel.org, hughd@google.com, baolin.wang@linux.alibaba.com, linmiaohe@huawei.com, nao.horiguchi@gmail.com, lorenzo@kernel.org, rppt@kernel.org, peterx@redhat.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v2 04/11] hugetlbfs,filemap: replace hugetlbfs_read_iter() with generic_file_read_iter() Message-ID: References: <20260617172534.1740152-1-jane.chu@oracle.com> <20260617172534.1740152-5-jane.chu@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260617172534.1740152-5-jane.chu@oracle.com> X-Rspamd-Queue-Id: C80D0180007 X-Rspam-User: X-Stat-Signature: t1tsm7hn3twzd4pdr61msre1exugg4oo X-Rspamd-Server: rspam09 X-HE-Tag: 1781726877-296861 X-HE-Meta: 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 JBdC3T/l oNcbWR/ZV6z8kIKNvxiomr30ONTFZIxApRClzB3yxTIqP3DAjnrEuKJpxmiQes5Rl6tqOwQE7L46uT++Snq1IqRDWahYdjs9/LeX6UOXnCXND2HyoATGklRmncqr2q5HeVKl8y5g2B4p7NfVafImsdHEvAwftLHqAv5qihEExC/sB2QwlLSswpUNNr2bA//Hptc8ABgRMxY3FNsHoHdxbmnD2fFX96CVMVesygjy26u5mZJXoyayHdoQFAI9ektBhvfv3yogP59Z7P6LuRgfxg24yJ3a9YnjSDtSPp5etPnb0lgygd3p0zsS7KdzPlu7cNhHBwZhRhRbowyAHIuRbM3cN42t+75YlS1Lfgd5u/eeunCNaDhNDYZytwSO30ijoaTSVvcVDBzOw8SE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jun 17, 2026 at 11:25:25AM -0600, Jane Chu wrote: > +++ b/mm/filemap.c > @@ -2672,20 +2672,30 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count, > { > struct file *filp = iocb->ki_filp; > struct address_space *mapping = filp->f_mapping; > + bool is_hugetlbfs = is_file_hugepages(filp); > pgoff_t index = iocb->ki_pos >> PAGE_SHIFT; > pgoff_t last_index; > struct folio *folio; > unsigned int flags; > + size_t min_folio_bytes; > int err = 0; > > /* "last_index" is the index of the folio beyond the end of the read */ > - last_index = round_up(iocb->ki_pos + count, > - mapping_min_folio_nrbytes(mapping)) >> PAGE_SHIFT; > + if (is_hugetlbfs) > + min_folio_bytes = huge_page_size(hstate_file(filp)); > + else > + min_folio_bytes = mapping_min_folio_nrbytes(mapping); > + last_index = round_up(iocb->ki_pos + count, min_folio_bytes) >> PAGE_SHIFT; I don't love this. Is there a way we can get mapping_min_folio_nrbytes() to give us the right number for hugetlbfs? I don't see why it wouldn't be possible ... > filemap_get_read_batch(mapping, index, last_index - 1, fbatch); > + > + if (is_hugetlbfs) > + goto done; We don't actually need this, do we? For hugetlbfs, I don't think we can get 0 folios in the batch, and then we won't find a folio with readahead set, and they're always uptodate ... so we're just skipping a few tests with this?