| Message ID | 20200131132350.31840-1-thenzl@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | megaraid_sas: silence a warning | expand |
On 1/31/20 5:23 AM, Tomas Henzl wrote: > Add a flag to dma mem allocation to silence a warning. > > Signed-off-by: Tomas Henzl <thenzl@redhat.com> > --- > drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c > index 0f5399b3e..1fa2d1449 100644 > --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c > +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c > @@ -606,7 +606,8 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) > > fusion->io_request_frames = > dma_pool_alloc(fusion->io_request_frames_pool, > - GFP_KERNEL, &fusion->io_request_frames_phys); > + GFP_KERNEL | __GFP_NOWARN, > + &fusion->io_request_frames_phys); > if (!fusion->io_request_frames) { > if (instance->max_fw_cmds >= (MEGASAS_REDUCE_QD_COUNT * 2)) { > instance->max_fw_cmds -= MEGASAS_REDUCE_QD_COUNT; > @@ -644,7 +645,7 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) > open-isns-updates.diff.bz2 > fusion->io_request_frames = > dma_pool_alloc(fusion->io_request_frames_pool, > - GFP_KERNEL, > + GFP_KERNEL | __GFP_NOWARN, > &fusion->io_request_frames_phys); > > if (!fusion->io_request_frames) { > I'm fairly sure this is a good fix, but I'd appreciate more information in the comment, such as what warning was silenced, and why it's okay to silence it rather than "fix" it. I know from experience that, when choosing which commits to backport, more information is better than less.
On Sat, Feb 1, 2020 at 10:57 PM Lee Duncan <lduncan@suse.com> wrote: > > On 1/31/20 5:23 AM, Tomas Henzl wrote: > > Add a flag to dma mem allocation to silence a warning. > > > > Signed-off-by: Tomas Henzl <thenzl@redhat.com> > > --- > > drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c > > index 0f5399b3e..1fa2d1449 100644 > > --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c > > +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c > > @@ -606,7 +606,8 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) > > > > fusion->io_request_frames = > > dma_pool_alloc(fusion->io_request_frames_pool, > > - GFP_KERNEL, &fusion->io_request_frames_phys); > > + GFP_KERNEL | __GFP_NOWARN, > > + &fusion->io_request_frames_phys); > > if (!fusion->io_request_frames) { > > if (instance->max_fw_cmds >= (MEGASAS_REDUCE_QD_COUNT * 2)) { > > instance->max_fw_cmds -= MEGASAS_REDUCE_QD_COUNT; > > @@ -644,7 +645,7 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) > > open-isns-updates.diff.bz2 > > fusion->io_request_frames = > > dma_pool_alloc(fusion->io_request_frames_pool, > > - GFP_KERNEL, > > + GFP_KERNEL | __GFP_NOWARN, > > &fusion->io_request_frames_phys); > > > > if (!fusion->io_request_frames) { > > > > I'm fairly sure this is a good fix, but I'd appreciate more information > in the comment, such as what warning was silenced, and why it's okay to > silence it rather than "fix" it. I know from experience that, when > choosing which commits to backport, more information is better than less. This code allocates DMA memory for driver's IO frames which may exceed MAX_ORDER pages for few megaraid_sas controllers(controllers with High Queue Depth). So there is logic to keep on reducing controller Queue Depth until DMA memory required for IO frames fits within MAX_ORDER. So or impacted megaraid_sas controllers, there would be multiple DMA allocation failure until driver settles down to Controller Queue Depth which has memory requirement within MAX_ORDER. These failed DMA allocation requests causes stack traces in system logs which is not harmful and this patch would silence those warnings/stack traces. With CMA (Contiguous Memory Allocator) enabled, it's possible to allocate DMA memory exceeding MAX_ORDER. And that is the reason of keeping this retry logic with less controller Queue Depth instead of calculating controller Queue depth at first hand which has memory requirement less than MAX_ORDER. Thanks, Sumit > > -- > Lee Duncan
On 2/3/20 10:16 AM, Sumit Saxena wrote: > On Sat, Feb 1, 2020 at 10:57 PM Lee Duncan <lduncan@suse.com> wrote: >> >> On 1/31/20 5:23 AM, Tomas Henzl wrote: >>> Add a flag to dma mem allocation to silence a warning. >>> >>> Signed-off-by: Tomas Henzl <thenzl@redhat.com> >>> --- >>> drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++-- >>> 1 file changed, 3 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c >>> index 0f5399b3e..1fa2d1449 100644 >>> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c >>> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c >>> @@ -606,7 +606,8 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) >>> >>> fusion->io_request_frames = >>> dma_pool_alloc(fusion->io_request_frames_pool, >>> - GFP_KERNEL, &fusion->io_request_frames_phys); >>> + GFP_KERNEL | __GFP_NOWARN, >>> + &fusion->io_request_frames_phys); >>> if (!fusion->io_request_frames) { >>> if (instance->max_fw_cmds >= (MEGASAS_REDUCE_QD_COUNT * 2)) { >>> instance->max_fw_cmds -= MEGASAS_REDUCE_QD_COUNT; >>> @@ -644,7 +645,7 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) >>> open-isns-updates.diff.bz2 >>> fusion->io_request_frames = >>> dma_pool_alloc(fusion->io_request_frames_pool, >>> - GFP_KERNEL, >>> + GFP_KERNEL | __GFP_NOWARN, >>> &fusion->io_request_frames_phys); >>> >>> if (!fusion->io_request_frames) { >>> >> >> I'm fairly sure this is a good fix, but I'd appreciate more information >> in the comment, such as what warning was silenced, and why it's okay to >> silence it rather than "fix" it. I know from experience that, when >> choosing which commits to backport, more information is better than less. > This code allocates DMA memory for driver's IO frames which may exceed > MAX_ORDER pages for few > megaraid_sas controllers(controllers with High Queue Depth). So there > is logic to keep on reducing controller > Queue Depth until DMA memory required for IO frames fits within > MAX_ORDER. So or impacted megaraid_sas controllers, > there would be multiple DMA allocation failure until driver settles > down to Controller Queue Depth which has memory requirement > within MAX_ORDER. These failed DMA allocation requests causes stack > traces in system logs which is not harmful and this patch > would silence those warnings/stack traces. > > With CMA (Contiguous Memory Allocator) enabled, it's possible to > allocate DMA memory exceeding MAX_ORDER. > And that is the reason of keeping this retry logic with less > controller Queue Depth instead of calculating controller Queue depth > at first hand which has memory requirement less than MAX_ORDER. Thank you Sumit for writing it down. An over-sized allocation failure is sanitized in a proper way. The warning may hide other allocation warnings in other parts of kernel as it is printed only once. I could have written more vecasue I've underestimated it and I'm sorry for that. Tomas > Thanks, > Sumit >> >> -- >> Lee Duncan >
On 2/3/20 4:20 AM, Tomas Henzl wrote: > On 2/3/20 10:16 AM, Sumit Saxena wrote: >> On Sat, Feb 1, 2020 at 10:57 PM Lee Duncan <lduncan@suse.com> wrote: >>> >>> On 1/31/20 5:23 AM, Tomas Henzl wrote: >>>> Add a flag to dma mem allocation to silence a warning. >>>> >>>> Signed-off-by: Tomas Henzl <thenzl@redhat.com> >>>> --- >>>> drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++-- >>>> 1 file changed, 3 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c >>>> index 0f5399b3e..1fa2d1449 100644 >>>> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c >>>> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c >>>> @@ -606,7 +606,8 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) >>>> >>>> fusion->io_request_frames = >>>> dma_pool_alloc(fusion->io_request_frames_pool, >>>> - GFP_KERNEL, &fusion->io_request_frames_phys); >>>> + GFP_KERNEL | __GFP_NOWARN, >>>> + &fusion->io_request_frames_phys); >>>> if (!fusion->io_request_frames) { >>>> if (instance->max_fw_cmds >= (MEGASAS_REDUCE_QD_COUNT * 2)) { >>>> instance->max_fw_cmds -= MEGASAS_REDUCE_QD_COUNT; >>>> @@ -644,7 +645,7 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) >>>> open-isns-updates.diff.bz2 >>>> fusion->io_request_frames = >>>> dma_pool_alloc(fusion->io_request_frames_pool, >>>> - GFP_KERNEL, >>>> + GFP_KERNEL | __GFP_NOWARN, >>>> &fusion->io_request_frames_phys); >>>> >>>> if (!fusion->io_request_frames) { >>>> >>> >>> I'm fairly sure this is a good fix, but I'd appreciate more information >>> in the comment, such as what warning was silenced, and why it's okay to >>> silence it rather than "fix" it. I know from experience that, when >>> choosing which commits to backport, more information is better than less. >> This code allocates DMA memory for driver's IO frames which may exceed >> MAX_ORDER pages for few >> megaraid_sas controllers(controllers with High Queue Depth). So there >> is logic to keep on reducing controller >> Queue Depth until DMA memory required for IO frames fits within >> MAX_ORDER. So or impacted megaraid_sas controllers, >> there would be multiple DMA allocation failure until driver settles >> down to Controller Queue Depth which has memory requirement >> within MAX_ORDER. These failed DMA allocation requests causes stack >> traces in system logs which is not harmful and this patch >> would silence those warnings/stack traces. >> >> With CMA (Contiguous Memory Allocator) enabled, it's possible to >> allocate DMA memory exceeding MAX_ORDER. >> And that is the reason of keeping this retry logic with less >> controller Queue Depth instead of calculating controller Queue depth >> at first hand which has memory requirement less than MAX_ORDER. > > Thank you Sumit for writing it down. > An over-sized allocation failure is sanitized in a proper way. The > warning may hide other allocation warnings in other parts of kernel as > it is printed only once. > > I could have written more vecasue I've underestimated it and I'm sorry > for that. > > Tomas No problem! Thank you for adding this. Can you resubmit with this info? If you're not familiar with submitting a 2nd version (V2), please look at the mailing list archives (or email me directly for advice). I'd be glad to add my reviewed tag once the patch is updated. > > >> Thanks, >> Sumit >>> >>> -- >>> Lee Duncan >> >
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c index 0f5399b3e..1fa2d1449 100644 --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c @@ -606,7 +606,8 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) fusion->io_request_frames = dma_pool_alloc(fusion->io_request_frames_pool, - GFP_KERNEL, &fusion->io_request_frames_phys); + GFP_KERNEL | __GFP_NOWARN, + &fusion->io_request_frames_phys); if (!fusion->io_request_frames) { if (instance->max_fw_cmds >= (MEGASAS_REDUCE_QD_COUNT * 2)) { instance->max_fw_cmds -= MEGASAS_REDUCE_QD_COUNT; @@ -644,7 +645,7 @@ megasas_alloc_request_fusion(struct megasas_instance *instance) fusion->io_request_frames = dma_pool_alloc(fusion->io_request_frames_pool, - GFP_KERNEL, + GFP_KERNEL | __GFP_NOWARN, &fusion->io_request_frames_phys); if (!fusion->io_request_frames) {
Add a flag to dma mem allocation to silence a warning. Signed-off-by: Tomas Henzl <thenzl@redhat.com> --- drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)