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Subject: Re: [syzbot] [block?] WARNING: suspicious RCU usage in mas_start (2)
Author: paolobertinetti200f4@proton.me

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 66eb55e71..7a64745e1 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -5628,6 +5628,8 @@ static bool ublk_try_buf_match(struct ublk_device *ub,
 	unsigned long expected_offset = 0;
 	bool first = true;
 
+	guard(rcu)();
+
 	rq_for_each_bvec(bv, rq, iter) {
 		unsigned long pfn = page_to_pfn(bv.bv_page);
 		unsigned long end_pfn = pfn +

base-commit: 93f51579e7df248780214094418f205253383cc5