Messages in this thread | | | From | Danielle Ratson <> | Subject | Re: [igb] netconsole triggers warning in netpoll_poll_dev | Date | Thu, 18 Nov 2021 15:30:35 +0000 |
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> On Thu, May 6, 2021 at 4:32 PM Jesse Brandeburg > <jesse.brandeburg@intel.com> wrote: > > > > Alexander Duyck wrote: > > > > > On Sun, Apr 25, 2021 at 11:47 PM Oleksandr Natalenko > > > <oleksandr@natalenko.name> wrote: > > > > > > > > Hello. > > > > > > > > On Fri, Apr 23, 2021 at 03:58:36PM -0700, Jakub Kicinski wrote: > > > > > On Fri, 23 Apr 2021 10:19:44 +0200 Oleksandr Natalenko wrote: > > > > > > On Wed, Apr 07, 2021 at 04:06:29PM -0700, Alexander Duyck wrote: > > > > > > > On Wed, Apr 7, 2021 at 11:07 AM Jakub Kicinski > <kuba@kernel.org> wrote: > > > > > > > > Sure, that's simplest. I wasn't sure something is supposed > > > > > > > > to prevent this condition or if it's okay to cover it up. > > > > > > > > > > > > > > I'm pretty sure it is okay to cover it up. In this case the > > > > > > > "budget - 1" is supposed to be the upper limit on what can > > > > > > > be reported. I think it was assuming an unsigned value anyway. > > > > > > > > > > > > > > Another alternative would be to default clean_complete to > !!budget. > > > > > > > Then if budget is 0 clean_complete would always return false. > > > > > > > > > > > > So, among all the variants, which one to try? Or there was a > > > > > > separate patch sent to address this? > > > > > > > > > > Alex's suggestion is probably best. > > > > > > > > > > I'm not aware of the fix being posted. Perhaps you could take > > > > > over and post the patch if Intel doesn't chime in? > > > > > > > > So, IIUC, Alex suggests this: > > > > > > > > ``` > > > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c > > > > b/drivers/net/ethernet/intel/igb/igb_main.c > > > > index a45cd2b416c8..7503d5bf168a 100644 > > > > --- a/drivers/net/ethernet/intel/igb/igb_main.c > > > > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > > > > @@ -7981,7 +7981,7 @@ static int igb_poll(struct napi_struct *napi, int > budget) > > > > struct igb_q_vector, > > > > napi); > > > > bool clean_complete = true; > > > > - int work_done = 0; > > > > + unsigned int work_done = 0; > > > > > > > > #ifdef CONFIG_IGB_DCA > > > > if (q_vector->adapter->flags & IGB_FLAG_DCA_ENABLED) @@ > > > > -8008,7 +8008,7 @@ static int igb_poll(struct napi_struct *napi, int > budget) > > > > if (likely(napi_complete_done(napi, work_done))) > > > > igb_ring_irq_enable(q_vector); > > > > > > > > - return min(work_done, budget - 1); > > > > + return min_t(unsigned int, work_done, budget - 1); > > > > } > > > > > > > > /** > > > > ``` > > > > > > > > Am I right? > > > > > > > > Thanks. > > > > > > Actually a better way to go would be to probably just initialize > > > "clean_complete = !!budget". With that we don't have it messing with > > > the interrupt enables which would probably be a better behavior. > > > > > > Thanks guys for the suggestions here! Finally got some time for this, > > so here is the patch I'm going to queue shortly. > > > > From ffd24e90d688ee347ab051266bfc7fca00324a68 Mon Sep 17 00:00:00 > 2001 > > From: Jesse Brandeburg <jesse.brandeburg@intel.com> > > Date: Thu, 6 May 2021 14:41:11 -0700 > > Subject: [PATCH net] igb: fix netpoll exit with traffic > > To: netdev, > > Oleksandr Natalenko <oleksandr@natalenko.name> > > Cc: Jakub Kicinski <kuba@kernel.org>, LKML > > <linux-kernel@vger.kernel.org>, "Brandeburg, Jesse" > > <jesse.brandeburg@intel.com>, "Nguyen, Anthony L" > > <anthony.l.nguyen@intel.com>, "David S. Miller" > <davem@davemloft.net>, > > intel-wired-lan <intel-wired-lan@lists.osuosl.org>, Alexander Duyck > > <alexander.duyck@gmail.com> > > > > Oleksandr brought a bug report where netpoll causes trace messages in > > the log on igb. > > > > [22038.710800] ------------[ cut here ]------------ [22038.710801] > > igb_poll+0x0/0x1440 [igb] exceeded budget in poll [22038.710802] > > WARNING: CPU: 12 PID: 40362 at net/core/netpoll.c:155 > > netpoll_poll_dev+0x18a/0x1a0 > > > > After some discussion and debug from the list, it was deemed that the > > right thing to do is initialize the clean_complete variable to false > > when the "netpoll mode" of passing a zero budget is used. > > > > This logic should be sane and not risky because the only time budget > > should be zero on entry is netpoll. Change includes a small refactor > > of local variable assignments to clean up the look. > > > > Fixes: 16eb8815c235 ("igb: Refactor clean_rx_irq to reduce overhead > > and improve performance") > > Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> > > Suggested-by: Alexander Duyck <alexander.duyck@gmail.com> > > Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com> > > --- > > > > Compile tested ONLY, but functionally it should be exactly the same > > for all cases except when budget is zero on entry, which will > > hopefully fix the bug. > > --- > > drivers/net/ethernet/intel/igb/igb_main.c | 12 ++++++++---- > > 1 file changed, 8 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c > > b/drivers/net/ethernet/intel/igb/igb_main.c > > index 0cd37ad81b4e..b0a9bed14071 100644 > > --- a/drivers/net/ethernet/intel/igb/igb_main.c > > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > > @@ -7991,12 +7991,16 @@ static void igb_ring_irq_enable(struct > igb_q_vector *q_vector) > > **/ > > static int igb_poll(struct napi_struct *napi, int budget) { > > - struct igb_q_vector *q_vector = container_of(napi, > > - struct igb_q_vector, > > - napi); > > - bool clean_complete = true; > > + struct igb_q_vector *q_vector; > > + bool clean_complete; > > int work_done = 0; > > > > + /* if budget is zero, we have a special case for netconsole, so > > + * make sure to set clean_complete to false in that case. > > + */ > > + clean_complete = !!budget; > > + > > + q_vector = container_of(napi, struct igb_q_vector, napi); > > #ifdef CONFIG_IGB_DCA > > if (q_vector->adapter->flags & IGB_FLAG_DCA_ENABLED) > > igb_update_dca(q_vector); > > I'm not a big fan of moving the q_vector init as a part of this patch since it > just means more backport work. > > That said the change itself should be harmless so I am good with it either > way. > > Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Hi,
I have lately added the netconsole module, and since then we see the same warning constantly in the logs. I have tried to apply Jesse's patch but it didn't seem to solve the issue.
Did anyone managed to solve the issue and can share with us?
Thanks, Danielle
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