linux-kernel - [PATCH] mm: trace tlb flush after disabling preemption in try_to_unmap

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]

Date:	Thu, 16 Jul 2015 15:35:39 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	akpm@...ux-foundation.org, mgorman@...e.de
Cc:	mhocko@...e.cz, riel@...hat.com, mingo@...nel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] mm: trace tlb flush after disabling preemption in try_to_unmap_flush

Commit "mm: send one IPI per CPU to TLB flush all entries after unmapping
pages" added a trace_tlb_flush() while preemption was still enabled. This
means that we'll access smp_processor_id() which in turn will get us quite
a few warnings.

Fix it by moving the trace to where the preemption is disabled, one line
down.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---

The diff is all lies: I've moved trace_tlb_flush() one line down rather
than get_cpu() a line up ;)

 mm/rmap.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 30812e9..63ba46c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -613,9 +613,10 @@ void try_to_unmap_flush(void)
 	if (!tlb_ubc->flush_required)
 		return;
 
+	cpu = get_cpu();
+
 	trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, -1UL);
 
-	cpu = get_cpu();
 	if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask))
 		percpu_flush_tlb_batch_pages(&tlb_ubc->cpumask);
 
-- 
1.7.10.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/