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Sun, 21 Dec 2025 18:29:46 -0500 (EST) From: Mathieu Desnoyers To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Mark Brown , linux-mm@kvack.org Subject: [PATCH v1 5/5] tsacct: Skip all kernel threads Date: Sun, 21 Dec 2025 18:29:26 -0500 Message-Id: <20251221232926.450602-6-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20251221232926.450602-1-mathieu.desnoyers@efficios.com> References: <20251221232926.450602-1-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: BEC201C0003 X-Rspamd-Server: rspam10 X-Stat-Signature: sw63erso9d5qww96p45rgcbzsehxe3hr X-HE-Tag: 1766359788-775840 X-HE-Meta: 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 jLwE7XMb YelQcqPeU14E9+IPjK5p/SJQIkWmQ++y/9kbvrHH9JUMRHB45aA507A6zBTzU9fACt3q91O0KI2OLkBAV599Nwcz9xCmFsV0UiGktfqyCbFwpRzKDwbsBiQgrSl/8saC+tIm/0lAoGyVhFaqBQ9PU88VBKRYVJnWlZusThH2luHVk/IOcAYIcVVOv6ot2ZH5vpykzYx6vM6ZeIv2rkT55gD8Qw7ctnW1vbJRq6J69nJUgF/qIhvguqbNUQVN14Kc4PioQX5PsP+KxkyQFLdZlAYdgjeTNrQA6+2jFwOr79cHZBX1whxp2dil4e/d2l5PvTfxsScDkhi1oOFGc2Epish8DEPsNoJuddszx3RV1Vz59ZlovIlNYmTdg2+EEkpbYm5VWdL+Ftu4IPwGbwgFphjPE/6K6VSz0UAfUoHgV3iY/WYhEgHO0exjdSA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When we hit acct_account_cputime within a irq handler over a kthread that happens to use a userspace mm, we end up summing up the mm's RSS into the tsk acct_rss_mem1, which eventually decays. I don't see a good rationale behind tracking the mm's rss in that way when a kthread use a userspace mm temporarily through use_mm. It causes issues with init_mm and efi_mm which only partially initialize their mm_struct. Skip all kernel threads in acct_account_cputime(), not just those that happen to have a NULL mm. Signed-off-by: Mathieu Desnoyers Cc: Andrew Morton Cc: Mark Brown Cc: linux-mm@kvack.org --- kernel/tsacct.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/tsacct.c b/kernel/tsacct.c index 6ea2f6363b90..3ef149b1245d 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -125,7 +125,7 @@ static void __acct_update_integrals(struct task_struct *tsk, { u64 time, delta; - if (!likely(tsk->mm)) + if (!tsk->mm || (tsk->flags & PF_KTHREAD)) return; time = stime + utime; -- 2.39.5