linux-kernel - [PATCH] dm verity: don't use WQ_MEM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240904040444.56070-1-ebiggers@kernel.org>
Date: Tue,  3 Sep 2024 21:04:44 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: dm-devel@...ts.linux.dev,
	Alasdair Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>
Cc: Tejun Heo <tj@...nel.org>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH] dm verity: don't use WQ_MEM_RECLAIM

From: Eric Biggers <ebiggers@...gle.com>

Since dm-verity doesn't support writes, the kernel's memory reclaim code
will never wait on dm-verity work.  That makes the use of WQ_MEM_RECLAIM
in dm-verity unnecessary.  WQ_MEM_RECLAIM has been present from the
beginning of dm-verity, but I could not find a justification for it;
I suspect it was just copied from dm-crypt which does support writes.

Therefore, remove WQ_MEM_RECLAIM from dm-verity.  This eliminates the
creation of an unnecessary rescuer thread per dm-verity device.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 drivers/md/dm-verity-target.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index cf659c8feb29f..051e84ca401dc 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -1488,11 +1488,11 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
 	 * allows verify_wq to preempt softirq since verification in BH workqueue
 	 * will fall-back to using it for error handling (or if the bufio cache
 	 * doesn't have required hashes).
 	 */
-	v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+	v->verify_wq = alloc_workqueue("kverityd", WQ_HIGHPRI, 0);
 	if (!v->verify_wq) {
 		ti->error = "Cannot allocate workqueue";
 		r = -ENOMEM;
 		goto bad;
 	}

base-commit: 88fac17500f4ea49c7bac136cf1b27e7b9980075
-- 
2.46.0