The patch below does not apply to the 6.12-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-6.12.y git checkout FETCH_HEAD git cherry-pick -x 5afb4bf9fc62d828647647ec31745083637132e4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025062950-football-lifting-1443@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 5afb4bf9fc62d828647647ec31745083637132e4 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov asml.silence@gmail.com Date: Tue, 24 Jun 2025 14:40:33 +0100 Subject: [PATCH] io_uring/rsrc: fix folio unpinning
syzbot complains about an unmapping failure:
[ 108.070381][ T14] kernel BUG at mm/gup.c:71! [ 108.070502][ T14] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP [ 108.123672][ T14] Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250221-8.fc42 02/21/2025 [ 108.127458][ T14] Workqueue: iou_exit io_ring_exit_work [ 108.174205][ T14] Call trace: [ 108.175649][ T14] sanity_check_pinned_pages+0x7cc/0x7d0 (P) [ 108.178138][ T14] unpin_user_page+0x80/0x10c [ 108.180189][ T14] io_release_ubuf+0x84/0xf8 [ 108.182196][ T14] io_free_rsrc_node+0x250/0x57c [ 108.184345][ T14] io_rsrc_data_free+0x148/0x298 [ 108.186493][ T14] io_sqe_buffers_unregister+0x84/0xa0 [ 108.188991][ T14] io_ring_ctx_free+0x48/0x480 [ 108.191057][ T14] io_ring_exit_work+0x764/0x7d8 [ 108.193207][ T14] process_one_work+0x7e8/0x155c [ 108.195431][ T14] worker_thread+0x958/0xed8 [ 108.197561][ T14] kthread+0x5fc/0x75c [ 108.199362][ T14] ret_from_fork+0x10/0x20
We can pin a tail page of a folio, but then io_uring will try to unpin the head page of the folio. While it should be fine in terms of keeping the page actually alive, mm folks say it's wrong and triggers a debug warning. Use unpin_user_folio() instead of unpin_user_page*.
Cc: stable@vger.kernel.org Debugged-by: David Hildenbrand david@redhat.com Reported-by: syzbot+1d335893772467199ab6@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/683f1551.050a0220.55ceb.0017.GAE@google.com Fixes: a8edbb424b139 ("io_uring/rsrc: enable multi-hugepage buffer coalescing") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/io-uring/a28b0f87339ac2acf14a645dad1e95bbcbf18acd.17... [axboe: adapt to current tree, massage commit message] Signed-off-by: Jens Axboe axboe@kernel.dk
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index d724602697e7..0c09e38784c9 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -112,8 +112,11 @@ static void io_release_ubuf(void *priv) struct io_mapped_ubuf *imu = priv; unsigned int i;
- for (i = 0; i < imu->nr_bvecs; i++) - unpin_user_page(imu->bvec[i].bv_page); + for (i = 0; i < imu->nr_bvecs; i++) { + struct folio *folio = page_folio(imu->bvec[i].bv_page); + + unpin_user_folio(folio, 1); + } }
static struct io_mapped_ubuf *io_alloc_imu(struct io_ring_ctx *ctx, @@ -840,8 +843,10 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx, if (ret) { if (imu) io_free_imu(ctx, imu); - if (pages) - unpin_user_pages(pages, nr_pages); + if (pages) { + for (i = 0; i < nr_pages; i++) + unpin_user_folio(page_folio(pages[i]), 1); + } io_cache_free(&ctx->node_cache, node); node = ERR_PTR(ret); }