| Message ID | 20210521083209.3740269-1-elver@google.com |
|---|---|
| State | Accepted |
| Commit | 8fd0e995cc7b6a7a8a40bc03d52a2cd445beeff4 |
| Headers | show |
| Series | kfence: use TASK_IDLE when awaiting allocation | expand |
On Fri, May 21, 2021 at 09:39AM +0000, David Laight wrote: > From: Marco Elver > > Sent: 21 May 2021 09:32 > > > > Since wait_event() uses TASK_UNINTERRUPTIBLE by default, waiting for an > > allocation counts towards load. However, for KFENCE, this does not make > > any sense, since there is no busy work we're awaiting. > > > > Instead, use TASK_IDLE via wait_event_idle() to not count towards load. > > Doesn't that let the process be interruptible by a signal. > Which is probably not desirable. > > There really ought to be a way of sleeping with TASK_UNINTERRUPTIBLE > without changing the load-average. That's what TASK_IDLE is: include/linux/sched.h:#define TASK_IDLE (TASK_UNINTERRUPTIBLE | TASK_NOLOAD) See https://lore.kernel.org/lkml/alpine.LFD.2.11.1505112154420.1749@ja.home.ssi.bg/T/ Thanks, -- Marco > IIRC the load-average is really intended to include processes > that are waiting for disk - especially for swap. > > David > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales)
Dear stable maintainers, The patch "kfence: use TASK_IDLE when awaiting allocation" has landed in mainline as 8fd0e995cc7b, however, does not apply cleanly to 5.12.y due to a prerequisite patch missing. My recommendation is to cherry-pick the following 2 commits to 5.12.y (rather than rebase 8fd0e995cc7b on top of 5.12.y): 37c9284f6932 kfence: maximize allocation wait timeout duration 8fd0e995cc7b kfence: use TASK_IDLE when awaiting allocation Many thanks, -- Marco ---------- Forwarded message --------- From: Marco Elver <elver@google.com> Date: Fri, 21 May 2021 at 10:32 Subject: [PATCH] kfence: use TASK_IDLE when awaiting allocation To: <elver@google.com>, <akpm@linux-foundation.org> Cc: <glider@google.com>, <dvyukov@google.com>, <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>, <kasan-dev@googlegroups.com>, Mel Gorman <mgorman@suse.de>, <stable@vger.kernel.org> Since wait_event() uses TASK_UNINTERRUPTIBLE by default, waiting for an allocation counts towards load. However, for KFENCE, this does not make any sense, since there is no busy work we're awaiting. Instead, use TASK_IDLE via wait_event_idle() to not count towards load. BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1185565 Fixes: 407f1d8c1b5f ("kfence: await for allocation using wait_event") Signed-off-by: Marco Elver <elver@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> # v5.12+ --- mm/kfence/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
On Mon, Jun 07, 2021 at 04:23:34PM +0200, Marco Elver wrote: > Dear stable maintainers, > > The patch "kfence: use TASK_IDLE when awaiting allocation" has landed > in mainline as 8fd0e995cc7b, however, does not apply cleanly to 5.12.y > due to a prerequisite patch missing. > > My recommendation is to cherry-pick the following 2 commits to 5.12.y > (rather than rebase 8fd0e995cc7b on top of 5.12.y): > > 37c9284f6932 kfence: maximize allocation wait timeout duration > 8fd0e995cc7b kfence: use TASK_IDLE when awaiting allocation Thanks, that worked! greg k-h
diff --git a/mm/kfence/core.c b/mm/kfence/core.c index e18fbbd5d9b4..4d21ac44d5d3 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -627,10 +627,10 @@ static void toggle_allocation_gate(struct work_struct *work) * During low activity with no allocations we might wait a * while; let's avoid the hung task warning. */ - wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), - sysctl_hung_task_timeout_secs * HZ / 2); + wait_event_idle_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), + sysctl_hung_task_timeout_secs * HZ / 2); } else { - wait_event(allocation_wait, atomic_read(&kfence_allocation_gate)); + wait_event_idle(allocation_wait, atomic_read(&kfence_allocation_gate)); } /* Disable static key and reset timer. */
Since wait_event() uses TASK_UNINTERRUPTIBLE by default, waiting for an allocation counts towards load. However, for KFENCE, this does not make any sense, since there is no busy work we're awaiting. Instead, use TASK_IDLE via wait_event_idle() to not count towards load. BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1185565 Fixes: 407f1d8c1b5f ("kfence: await for allocation using wait_event") Signed-off-by: Marco Elver <elver@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: <stable@vger.kernel.org> # v5.12+ --- mm/kfence/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)