From 917ff75e9510d19968ef3cc5c80b1cd0ef48f84d Mon Sep 17 00:00:00 2001 From: Rob N Date: Thu, 4 Apr 2024 09:17:07 +1100 Subject: [PATCH] vdev_disk: don't touch vbio after its handed off to the kernel MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After IO is unplugged, it may complete immediately and vbio_completion be called on interrupt context. That may interrupt or deschedule our task. If its the last bio, the vbio will be freed. Then, we get rescheduled, and try to write to freed memory through vbio->. This patch just removes the the cleanup, and the corresponding assert. These were leftovers from a previous iteration of vbio_submit() and were always "belt and suspenders" ops anyway, never strictly required. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc Reported-by: Rich Ercolani Reviewed-by: Laurențiu Nicola Reviewed-by: Alexander Motin Reviewed-by: George Wilson Signed-off-by: Rob Norris Closes #16045 Closes #16050 Closes #16049 --- module/os/linux/zfs/vdev_disk.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c index ac8fe6cb1b..df5fa06779 100644 --- a/module/os/linux/zfs/vdev_disk.c +++ b/module/os/linux/zfs/vdev_disk.c @@ -755,8 +755,6 @@ vbio_fill_cb(struct page *page, size_t off, size_t len, void *priv) static void vbio_submit(vbio_t *vbio, abd_t *abd, uint64_t size) { - ASSERT(vbio->vbio_bdev); - /* * We plug so we can submit the BIOs as we go and only unplug them when * they are fully created and submitted. This is important; if we don't @@ -774,12 +772,15 @@ vbio_submit(vbio_t *vbio, abd_t *abd, uint64_t size) vbio->vbio_bio->bi_end_io = vbio_completion; vbio->vbio_bio->bi_private = vbio; + /* + * Once submitted, vbio_bio now owns vbio (through bi_private) and we + * can't touch it again. The bio may complete and vbio_completion() be + * called and free the vbio before this task is run again, so we must + * consider it invalid from this point. + */ vdev_submit_bio(vbio->vbio_bio); blk_finish_plug(&plug); - - vbio->vbio_bio = NULL; - vbio->vbio_bdev = NULL; } /* IO completion callback */