The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x 1b151e2435fc3a9b10c8946c6aebe9f3e1938c55 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024012229-dealer-luster-6ff4@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

1b151e2435fc ("block: Remove special-casing of compound pages") fd363244e883 ("block: Add BIO_PAGE_PINNED and associated infrastructure") e51bab4e2058 ("block: Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED with inverted logic") a450f49708ea ("iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing") 7ee4ccf57484 ("block: set FOLL_PCI_P2PDMA in bio_map_user_iov()") 80bd4a7aab4c ("blk-mq: move the srcu_struct used for quiescing to the tagset") e88811bc43b9 ("block: use on-stack page vec for <= UIO_FASTIOV") 480cb846c27b ("block: convert to advancing variants of iov_iter_get_pages{,_alloc}()") e97424fd4472 ("block: fix leaking page ref on truncated direct io") 34cdb8c825f2 ("block: ensure bio_iov_add_page can't fail") 325347d965e7 ("block: ensure iov_iter advances for added pages") 46754bd05605 ("block: move ->bio_split to the gendisk") 5a97806f7dc0 ("block: change the blk_queue_split calling convention") 8374cfe647a1 ("Merge tag 'for-6.0/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1b151e2435fc3a9b10c8946c6aebe9f3e1938c55 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" willy@infradead.org Date: Mon, 14 Aug 2023 15:41:00 +0100 Subject: [PATCH] block: Remove special-casing of compound pages

The special casing was originally added in pre-git history; reproducing the commit log here:

commit a318a92567d77 Author: Andrew Morton akpm@osdl.org Date: Sun Sep 21 01:42:22 2003 -0700

[PATCH] Speed up direct-io hugetlbpage handling

This patch short-circuits all the direct-io page dirtying logic for
higher-order pages.  Without this, we pointlessly bounce BIOs up to
keventd all the time.

In the last twenty years, compound pages have become used for more than just hugetlb. Rewrite these functions to operate on folios instead of pages and remove the special case for hugetlbfs; I don't think it's needed any more (and if it is, we can put it back in as a call to folio_test_hugetlb()).

This was found by inspection; as far as I can tell, this bug can lead to pages used as the destination of a direct I/O read not being marked as dirty. If those pages are then reclaimed by the MM without being dirtied for some other reason, they won't be written out. Then when they're faulted back in, they will not contain the data they should. It'll take a pretty unusual setup to produce this problem with several races all going the wrong way.

This problem predates the folio work; it could for example have been triggered by mmaping a THP in tmpfs and using that as the target of an O_DIRECT read.

Fixes: 800d8c63b2e98 ("shmem: add huge pages support") Cc: stable@vger.kernel.org Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/block/bio.c b/block/bio.c index 816d412c06e9..5eba53ca953b 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1145,13 +1145,22 @@ EXPORT_SYMBOL(bio_add_folio);

void __bio_release_pages(struct bio *bio, bool mark_dirty) { - struct bvec_iter_all iter_all; - struct bio_vec *bvec; + struct folio_iter fi; + + bio_for_each_folio_all(fi, bio) { + struct page *page; + size_t done = 0;

- bio_for_each_segment_all(bvec, bio, iter_all) { - if (mark_dirty && !PageCompound(bvec->bv_page)) - set_page_dirty_lock(bvec->bv_page); - bio_release_page(bio, bvec->bv_page); + if (mark_dirty) { + folio_lock(fi.folio); + folio_mark_dirty(fi.folio); + folio_unlock(fi.folio); + } + page = folio_page(fi.folio, fi.offset / PAGE_SIZE); + do { + bio_release_page(bio, page++); + done += PAGE_SIZE; + } while (done < fi.length); } } EXPORT_SYMBOL_GPL(__bio_release_pages); @@ -1439,18 +1448,12 @@ EXPORT_SYMBOL(bio_free_pages); * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions * for performing direct-IO in BIOs. * - * The problem is that we cannot run set_page_dirty() from interrupt context + * The problem is that we cannot run folio_mark_dirty() from interrupt context * because the required locks are not interrupt-safe. So what we can do is to * mark the pages dirty _before_ performing IO. And in interrupt context, * check that the pages are still dirty. If so, fine. If not, redirty them * in process context. * - * We special-case compound pages here: normally this means reads into hugetlb - * pages. The logic in here doesn't really work right for compound pages - * because the VM does not uniformly chase down the head page in all cases. - * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't - * handle them at all. So we skip compound pages here at an early stage. - * * Note that this code is very hard to test under normal circumstances because * direct-io pins the pages with get_user_pages(). This makes * is_page_cache_freeable return false, and the VM will not clean the pages. @@ -1466,12 +1469,12 @@ EXPORT_SYMBOL(bio_free_pages); */ void bio_set_pages_dirty(struct bio *bio) { - struct bio_vec *bvec; - struct bvec_iter_all iter_all; + struct folio_iter fi;

- bio_for_each_segment_all(bvec, bio, iter_all) { - if (!PageCompound(bvec->bv_page)) - set_page_dirty_lock(bvec->bv_page); + bio_for_each_folio_all(fi, bio) { + folio_lock(fi.folio); + folio_mark_dirty(fi.folio); + folio_unlock(fi.folio); } } EXPORT_SYMBOL_GPL(bio_set_pages_dirty); @@ -1515,12 +1518,11 @@ static void bio_dirty_fn(struct work_struct *work)

void bio_check_pages_dirty(struct bio *bio) { - struct bio_vec *bvec; + struct folio_iter fi; unsigned long flags; - struct bvec_iter_all iter_all;

- bio_for_each_segment_all(bvec, bio, iter_all) { - if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page)) + bio_for_each_folio_all(fi, bio) { + if (!folio_test_dirty(fi.folio)) goto defer; }