From: Pavel Begunkov Date: Sun, 8 Dec 2024 21:46:01 +0000 (+0000) Subject: io_uring: don't vmap single page regions X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=de3b9e2e48190be28473ea84c384bc64931facf7;p=users%2Fjedix%2Flinux-maple.git io_uring: don't vmap single page regions When io_check_coalesce_buffer() meets a single page buffer it bails out and tells that it can be coalesced. That's fine for registered buffers as io_coalesce_buffer() wouldn't change anything, but the region code now uses the function to decided on whether to vmap the buffer or not. Report that a single page buffer is trivially coalescable and let io_sqe_buffer_register() to filter them. Fixes: c4d0ac1c1567 ("io_uring/memmap: optimise single folio regions") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/cb83e053f318857068447d40c95becebcd8aeced.1733689833.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 2d2333970eb53..f2ff108485c85 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -675,14 +675,9 @@ bool io_check_coalesce_buffer(struct page **page_array, int nr_pages, unsigned int count = 1, nr_folios = 1; int i; - if (nr_pages <= 1) - return false; - data->nr_pages_mid = folio_nr_pages(folio); - if (data->nr_pages_mid == 1) - return false; - data->folio_shift = folio_shift(folio); + /* * Check if pages are contiguous inside a folio, and all folios have * the same page count except for the head and tail. @@ -750,8 +745,10 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx, } /* If it's huge page(s), try to coalesce them into fewer bvec entries */ - if (io_check_coalesce_buffer(pages, nr_pages, &data)) - coalesced = io_coalesce_buffer(&pages, &nr_pages, &data); + if (nr_pages > 1 && io_check_coalesce_buffer(pages, nr_pages, &data)) { + if (data.nr_pages_mid != 1) + coalesced = io_coalesce_buffer(&pages, &nr_pages, &data); + } imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL); if (!imu)