| Message ID | 20180427130811.7642-1-michel@daenzer.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Apr 27, 2018 at 9:08 AM, Michel Dänzer <michel@daenzer.net> wrote: > From: Michel Dänzer <michel.daenzer@amd.com> > > Previously, TTM would always (with CONFIG_TRANSPARENT_HUGEPAGE enabled) > try to allocate huge pages. However, not all drivers can take advantage > of huge pages, but they would incur the overhead for allocating and > freeing them anyway. > > Now, drivers which can take advantage of huge pages need to set the new > flag TTM_PAGE_FLAG_TRANSHUGE to get them. Drivers not setting this flag > no longer incur any overhead for allocating or freeing huge pages. > > v2: > * Also guard swapping of consecutive pages in ttm_get_pages > * Reword commit log, hopefully clearer now > > Cc: stable@vger.kernel.org > Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> Both I and lots of other people, based on reports, are still seeing plenty of issues with this as late as 4.16.4. Admittedly I'm on nouveau, but others have reported issues with radeon/amdgpu as well. It's been going on since the feature was merged in v4.15, with what seems like little investigation from the authors introducing the feature. We now have *two* broken releases, v4.15 and v4.16 (anything that spews error messages and stack traces ad-infinitum in dmesg is, by definition, broken). You're putting this behind a flag now (finally), but should it be enabled anywhere? Why is it being flipped on for amdgpu by default, despite the still-existing problems? Reverting this feature without just resetting back to the code in v4.14 is painful, but why make Joe User suffer by enabling it while you're still working out the kinks? -ilia
On 2018-04-28 06:30 PM, Ilia Mirkin wrote: > On Fri, Apr 27, 2018 at 9:08 AM, Michel Dänzer <michel@daenzer.net> wrote: >> From: Michel Dänzer <michel.daenzer@amd.com> >> >> Previously, TTM would always (with CONFIG_TRANSPARENT_HUGEPAGE enabled) >> try to allocate huge pages. However, not all drivers can take advantage >> of huge pages, but they would incur the overhead for allocating and >> freeing them anyway. >> >> Now, drivers which can take advantage of huge pages need to set the new >> flag TTM_PAGE_FLAG_TRANSHUGE to get them. Drivers not setting this flag >> no longer incur any overhead for allocating or freeing huge pages. >> >> v2: >> * Also guard swapping of consecutive pages in ttm_get_pages >> * Reword commit log, hopefully clearer now >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> > > Both I and lots of other people, based on reports, are still seeing > plenty of issues with this as late as 4.16.4. "lots of other people", "plenty of issues" sounds a bit exaggerated from what I've seen. FWIW, while I did see the original messages myself, I haven't seen any since Christian's original fix (see below), neither with amdgpu nor radeon, even before this patch you followed up to. > Admittedly I'm on nouveau, but others have reported issues with > radeon/amdgpu as well. It's been going on since the feature was merged > in v4.15, with what seems like little investigation from the authors > introducing the feature. That's not a fair assessment. See https://bugs.freedesktop.org/show_bug.cgi?id=104082#c40 and following comments. Christian fixed the original issue in d0bc0c2a31c95002d37c3cc511ffdcab851b3256 "swiotlb: suppress warning when __GFP_NOWARN is set". Christian did his best to try and get the fix in before 4.15 final, but for reasons beyond his control, it was delayed until 4.16-rc1 and then backported to 4.15.5. Unfortunately, there was an swiotlb regression (not directly related to Christian's work) shortly after this fix, also in 4.16-rc1, which is now fixed in 4.17-rc1 and will be backported to 4.16.y. It looks like there's at least one more bug left, but it's not clear yet when that was introduced, whether it's directly related to Christian's work, or indeed what the impact is. Let's not get ahead of ourselves. > We now have *two* broken releases, v4.15 and v4.16 (anything that > spews error messages and stack traces ad-infinitum in dmesg is, by > definition, broken). I haven't seen any evidence that there's still an issue in 4.15, is there any? > You're putting this behind a flag now (finally), I wrote this patch because I realized due to some remark I happened to see you make this week on IRC that the huge page support in TTM was enabled for all drivers. Instead of making that kind of remark on IRC, it would have been more constructive, and more conducive to quick implementation, to suggest making the feature not active for drivers which don't need it in a mailing list post. At least, please do more research before making this kind of negative post. P.S. You might also want to look into whether nouveau really should be hitting swiotlb in these cases.
On Sat, Apr 28, 2018 at 7:02 PM, Michel Dänzer <michel@daenzer.net> wrote: > On 2018-04-28 06:30 PM, Ilia Mirkin wrote: >> On Fri, Apr 27, 2018 at 9:08 AM, Michel Dänzer <michel@daenzer.net> wrote: >>> From: Michel Dänzer <michel.daenzer@amd.com> >>> >>> Previously, TTM would always (with CONFIG_TRANSPARENT_HUGEPAGE enabled) >>> try to allocate huge pages. However, not all drivers can take advantage >>> of huge pages, but they would incur the overhead for allocating and >>> freeing them anyway. >>> >>> Now, drivers which can take advantage of huge pages need to set the new >>> flag TTM_PAGE_FLAG_TRANSHUGE to get them. Drivers not setting this flag >>> no longer incur any overhead for allocating or freeing huge pages. >>> >>> v2: >>> * Also guard swapping of consecutive pages in ttm_get_pages >>> * Reword commit log, hopefully clearer now >>> >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> >> >> Both I and lots of other people, based on reports, are still seeing >> plenty of issues with this as late as 4.16.4. > > "lots of other people", "plenty of issues" sounds a bit exaggerated from > what I've seen. FWIW, while I did see the original messages myself, I > haven't seen any since Christian's original fix (see below), neither > with amdgpu nor radeon, even before this patch you followed up to. Probably a half-dozen reports of it with nouveau, in addition to another bunch of people talking about it on the bug you mention below, along with email threads on dri-devel. I figured I didn't have to raise my own since it was identical to the others, and, I assumed, was being handled. >> Admittedly I'm on nouveau, but others have reported issues with >> radeon/amdgpu as well. It's been going on since the feature was merged >> in v4.15, with what seems like little investigation from the authors >> introducing the feature. > > That's not a fair assessment. See > https://bugs.freedesktop.org/show_bug.cgi?id=104082#c40 and following > comments. > > Christian fixed the original issue in > d0bc0c2a31c95002d37c3cc511ffdcab851b3256 "swiotlb: suppress warning when > __GFP_NOWARN is set". Christian did his best to try and get the fix in > before 4.15 final, but for reasons beyond his control, it was delayed > until 4.16-rc1 and then backported to 4.15.5. In case it's unclear, let me state this explicitly -- I totally get that despite best intentions, bugs get introduced. I do it myself. What I'm having trouble with is the handling once the issue is discovered. > > Unfortunately, there was an swiotlb regression (not directly related to > Christian's work) shortly after this fix, also in 4.16-rc1, which is now > fixed in 4.17-rc1 and will be backported to 4.16.y. https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=v4.16.5&id=2c9dacf5bfe1e45d96dfe97cb71d2b717786a7b9 This guy? Didn't help. I'm running 4.16.4 right now. > It looks like there's at least one more bug left, but it's not clear yet > when that was introduced, whether it's directly related to Christian's > work, or indeed what the impact is. Let's not get ahead of ourselves. Whether it is directly related to that work or not, the issue persists. There are two options: - When declaring things fixed, no serious attempt was actually made at reproducing the underlying issues. - The authors truly can't reproduce the underlying issues users are seeing and are taking stabs in the dark. Given that a number of people are reporting problems, in either scenario, the reasonable thing is to disable the feature, and figure out what is going on. Maybe condition it on !CONFIG_SWIOTLB. >> We now have *two* broken releases, v4.15 and v4.16 (anything that >> spews error messages and stack traces ad-infinitum in dmesg is, by >> definition, broken). > > I haven't seen any evidence that there's still an issue in 4.15, is > there any? Well, I did have a late 4.15 rc kernel in addition to the 'suppress warning' patch. Now I'm questioning my memory of whether the issue was resolved there or not. I'm pretty sure that 'not', but no longer 100%. Either way, I think we all agree v4.15 was broken and more importantly was *known* to be broken well in advance of the release. A reasonable option would have been to disable the feature until the other bits fell into place. >> You're putting this behind a flag now (finally), > > I wrote this patch because I realized due to some remark I happened to > see you make this week on IRC that the huge page support in TTM was > enabled for all drivers. Instead of making that kind of remark on IRC, > it would have been more constructive, and more conducive to quick > implementation, to suggest making the feature not active for drivers > which don't need it in a mailing list post. I see IRC as a much faster and direct way of reaching the authors and/or people who need to know an issue. As there was already a bug filed about it and the issue was known about, I didn't really see a reason to pile on (until now). > At least, please do more research before making this kind of negative > post. Every time I've reported it, I've been told that patch X definitely solves the issue. There was the original fix from Christian which went into v4.15 and I'm pretty sure didn't fix it (I had it applied to a 4.15 tree), and then the later issue with the swiotlb logic inversion bug which also didn't fix it. It's entirely possible that the true issue lies not in the code that was written as part of this feature enablement but rather existing code in handling of thp. But the end result is that I have a broken kernel. As a user who is not in a position to debug this directly due to lack of time and knowledge, my options are limited. This issue hasn't gotten a ton of visibility since it's waved away every time as "fixed", so I'm trying to turn up the heat a little bit to cause a fix or revert to happen. I believe the policy in Linux is "no regressions", unlike many other graphics components where regressions are welcome as long as they're downstream components of where the change is made. > P.S. You might also want to look into whether nouveau really should be > hitting swiotlb in these cases. I don't have a strong enough concept of what the swiotlb does and when it's needed. Hopefully someone that does will take a look. -ilia
Am 29.04.2018 um 01:02 schrieb Michel Dänzer: > On 2018-04-28 06:30 PM, Ilia Mirkin wrote: >> On Fri, Apr 27, 2018 at 9:08 AM, Michel Dänzer <michel@daenzer.net> wrote: >>> From: Michel Dänzer <michel.daenzer@amd.com> >>> >>> Previously, TTM would always (with CONFIG_TRANSPARENT_HUGEPAGE enabled) >>> try to allocate huge pages. However, not all drivers can take advantage >>> of huge pages, but they would incur the overhead for allocating and >>> freeing them anyway. >>> >>> Now, drivers which can take advantage of huge pages need to set the new >>> flag TTM_PAGE_FLAG_TRANSHUGE to get them. Drivers not setting this flag >>> no longer incur any overhead for allocating or freeing huge pages. >>> >>> v2: >>> * Also guard swapping of consecutive pages in ttm_get_pages >>> * Reword commit log, hopefully clearer now >>> >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> >> Both I and lots of other people, based on reports, are still seeing >> plenty of issues with this as late as 4.16.4. > "lots of other people", "plenty of issues" sounds a bit exaggerated from > what I've seen. FWIW, while I did see the original messages myself, I > haven't seen any since Christian's original fix (see below), neither > with amdgpu nor radeon, even before this patch you followed up to. > > >> Admittedly I'm on nouveau, but others have reported issues with >> radeon/amdgpu as well. It's been going on since the feature was merged >> in v4.15, with what seems like little investigation from the authors >> introducing the feature. > That's not a fair assessment. See > https://bugs.freedesktop.org/show_bug.cgi?id=104082#c40 and following > comments. > > Christian fixed the original issue in > d0bc0c2a31c95002d37c3cc511ffdcab851b3256 "swiotlb: suppress warning when > __GFP_NOWARN is set". Christian did his best to try and get the fix in > before 4.15 final, but for reasons beyond his control, it was delayed > until 4.16-rc1 and then backported to 4.15.5. > > Unfortunately, there was an swiotlb regression (not directly related to > Christian's work) shortly after this fix, also in 4.16-rc1, which is now > fixed in 4.17-rc1 and will be backported to 4.16.y. And that's exactly the reason why I intentionally kept this enabled for all users of the TTM DMA page pool and not put it behind a flag. This change has surfaced quite a number of bugs in the swiotlb code which could have caused issues before. It's just that those code path where never exercised massively before. Additional to that using huge pages is beneficial for the MM and CPU TLB (not implemented yet) even when the GPU driver can't make much use of it. > It looks like there's at least one more bug left, but it's not clear yet > when that was introduced, whether it's directly related to Christian's > work, or indeed what the impact is. Let's not get ahead of ourselves. Well my patches surfaced the problems, but the underlying issues where present even before those changes and I'm very well involved in fixing the underlying issues. I even considered to just revert the huge page path for the DMA pool allocator, but it's just that the TTM patches seem to work exactly as they are intended. So that doesn't feel like doing the right thing here. >> We now have *two* broken releases, v4.15 and v4.16 (anything that >> spews error messages and stack traces ad-infinitum in dmesg is, by >> definition, broken). > I haven't seen any evidence that there's still an issue in 4.15, is > there any? Not that I know of, the fix was backported as far as I know. >> You're putting this behind a flag now (finally), > I wrote this patch because I realized due to some remark I happened to > see you make this week on IRC that the huge page support in TTM was > enabled for all drivers. Instead of making that kind of remark on IRC, > it would have been more constructive, and more conducive to quick > implementation, to suggest making the feature not active for drivers > which don't need it in a mailing list post. I have to admit that I'm lacking behind taking care of the amdgpu/radeon user space issues just because of more important stuff to do, but the issues affecting other drivers should be fixed by now. BTW: The user space problems for amdgpu/radeon seems to come from either the DDX or Glamour. For example try playing a video user firefox with Glamour enabled and take a look at how much memory we free/allocate. It's multiple gigabytes for just a few seconds playback, that strongly indicates that we allocate/free a texture for each displayed frame which is quite far from optimal. Regards, Christian. > > > At least, please do more research before making this kind of negative > post. > > P.S. You might also want to look into whether nouveau really should be > hitting swiotlb in these cases. >
On 2018-04-29 09:02 AM, Christian König wrote: > Am 29.04.2018 um 01:02 schrieb Michel Dänzer: >> On 2018-04-28 06:30 PM, Ilia Mirkin wrote: >>> On Fri, Apr 27, 2018 at 9:08 AM, Michel Dänzer <michel@daenzer.net> >>> wrote: >>>> From: Michel Dänzer <michel.daenzer@amd.com> >>>> >>>> Previously, TTM would always (with CONFIG_TRANSPARENT_HUGEPAGE enabled) >>>> try to allocate huge pages. However, not all drivers can take advantage >>>> of huge pages, but they would incur the overhead for allocating and >>>> freeing them anyway. >>>> >>>> Now, drivers which can take advantage of huge pages need to set the new >>>> flag TTM_PAGE_FLAG_TRANSHUGE to get them. Drivers not setting this flag >>>> no longer incur any overhead for allocating or freeing huge pages. >>>> >>>> v2: >>>> * Also guard swapping of consecutive pages in ttm_get_pages >>>> * Reword commit log, hopefully clearer now >>>> >>>> Cc: stable@vger.kernel.org >>>> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> >>> Both I and lots of other people, based on reports, are still seeing >>> plenty of issues with this as late as 4.16.4. >> "lots of other people", "plenty of issues" sounds a bit exaggerated from >> what I've seen. FWIW, while I did see the original messages myself, I >> haven't seen any since Christian's original fix (see below), neither >> with amdgpu nor radeon, even before this patch you followed up to. >> >> >>> Admittedly I'm on nouveau, but others have reported issues with >>> radeon/amdgpu as well. It's been going on since the feature was merged >>> in v4.15, with what seems like little investigation from the authors >>> introducing the feature. >> That's not a fair assessment. See >> https://bugs.freedesktop.org/show_bug.cgi?id=104082#c40 and following >> comments. >> >> Christian fixed the original issue in >> d0bc0c2a31c95002d37c3cc511ffdcab851b3256 "swiotlb: suppress warning when >> __GFP_NOWARN is set". Christian did his best to try and get the fix in >> before 4.15 final, but for reasons beyond his control, it was delayed >> until 4.16-rc1 and then backported to 4.15.5. >> >> Unfortunately, there was an swiotlb regression (not directly related to >> Christian's work) shortly after this fix, also in 4.16-rc1, which is now >> fixed in 4.17-rc1 and will be backported to 4.16.y. > > And that's exactly the reason why I intentionally kept this enabled for > all users of the TTM DMA page pool and not put it behind a flag. > > This change has surfaced quite a number of bugs in the swiotlb code > which could have caused issues before. It's just that those code path > where never exercised massively before. > > Additional to that using huge pages is beneficial for the MM and CPU TLB > (not implemented yet) even when the GPU driver can't make much use of it. Do I understand correctly that you're against this patch? AFAIU the only benefit of huge pages with a driver which doesn't take advantage of them directly is "for the MM". Can you describe a bit more what that benefit is exactly? Is it expected to outweigh the cost of allocating / freeing huge pages? >> It looks like there's at least one more bug left, but it's not clear yet >> when that was introduced, whether it's directly related to Christian's >> work, or indeed what the impact is. Let's not get ahead of ourselves. > > Well my patches surfaced the problems, but the underlying issues where > present even before those changes and I'm very well involved in fixing > the underlying issues. > > I even considered to just revert the huge page path for the DMA pool > allocator, but it's just that the TTM patches seem to work exactly as > they are intended. So that doesn't feel like doing the right thing here. I agree. Has anyone reported this to the DMA/SWIOTLB developers?
Am 30.04.2018 um 18:33 schrieb Michel Dänzer: > On 2018-04-29 09:02 AM, Christian König wrote: >> Am 29.04.2018 um 01:02 schrieb Michel Dänzer: >>> On 2018-04-28 06:30 PM, Ilia Mirkin wrote: >>>> On Fri, Apr 27, 2018 at 9:08 AM, Michel Dänzer <michel@daenzer.net> >>>> wrote: >>>>> From: Michel Dänzer <michel.daenzer@amd.com> >>>>> >>>>> Previously, TTM would always (with CONFIG_TRANSPARENT_HUGEPAGE enabled) >>>>> try to allocate huge pages. However, not all drivers can take advantage >>>>> of huge pages, but they would incur the overhead for allocating and >>>>> freeing them anyway. >>>>> >>>>> Now, drivers which can take advantage of huge pages need to set the new >>>>> flag TTM_PAGE_FLAG_TRANSHUGE to get them. Drivers not setting this flag >>>>> no longer incur any overhead for allocating or freeing huge pages. >>>>> >>>>> v2: >>>>> * Also guard swapping of consecutive pages in ttm_get_pages >>>>> * Reword commit log, hopefully clearer now >>>>> >>>>> Cc: stable@vger.kernel.org >>>>> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> >>>> Both I and lots of other people, based on reports, are still seeing >>>> plenty of issues with this as late as 4.16.4. >>> "lots of other people", "plenty of issues" sounds a bit exaggerated from >>> what I've seen. FWIW, while I did see the original messages myself, I >>> haven't seen any since Christian's original fix (see below), neither >>> with amdgpu nor radeon, even before this patch you followed up to. >>> >>> >>>> Admittedly I'm on nouveau, but others have reported issues with >>>> radeon/amdgpu as well. It's been going on since the feature was merged >>>> in v4.15, with what seems like little investigation from the authors >>>> introducing the feature. >>> That's not a fair assessment. See >>> https://bugs.freedesktop.org/show_bug.cgi?id=104082#c40 and following >>> comments. >>> >>> Christian fixed the original issue in >>> d0bc0c2a31c95002d37c3cc511ffdcab851b3256 "swiotlb: suppress warning when >>> __GFP_NOWARN is set". Christian did his best to try and get the fix in >>> before 4.15 final, but for reasons beyond his control, it was delayed >>> until 4.16-rc1 and then backported to 4.15.5. >>> >>> Unfortunately, there was an swiotlb regression (not directly related to >>> Christian's work) shortly after this fix, also in 4.16-rc1, which is now >>> fixed in 4.17-rc1 and will be backported to 4.16.y. >> And that's exactly the reason why I intentionally kept this enabled for >> all users of the TTM DMA page pool and not put it behind a flag. >> >> This change has surfaced quite a number of bugs in the swiotlb code >> which could have caused issues before. It's just that those code path >> where never exercised massively before. >> >> Additional to that using huge pages is beneficial for the MM and CPU TLB >> (not implemented yet) even when the GPU driver can't make much use of it. > Do I understand correctly that you're against this patch? Not completely, I've considered adding that multiple times myself. I'm just torn apart between keeping it enabled so that the underlying bugs gets fixed and disabling it for a better end user experience. But in general I would opt out for a pool configuration option, not a per driver flag. > AFAIU the only benefit of huge pages with a driver which doesn't take > advantage of them directly is "for the MM". Can you describe a bit more > what that benefit is exactly? When transparent huge pages are in effect we should have more huge pages than small pages in the system allocator. So by enforcing allocation of small pages we fragment the huge pages once more and give khugepaged quite a bunch of work todo to gather them together into huge pages again. > Is it expected to outweigh the cost of allocating / freeing huge pages? Yes, and actually quite well (at least in theory). >>> It looks like there's at least one more bug left, but it's not clear yet >>> when that was introduced, whether it's directly related to Christian's >>> work, or indeed what the impact is. Let's not get ahead of ourselves. >> Well my patches surfaced the problems, but the underlying issues where >> present even before those changes and I'm very well involved in fixing >> the underlying issues. >> >> I even considered to just revert the huge page path for the DMA pool >> allocator, but it's just that the TTM patches seem to work exactly as >> they are intended. So that doesn't feel like doing the right thing here. > I agree. Has anyone reported this to the DMA/SWIOTLB developers? Yes, I fixed the original false positive messages myself with the swiotlb maintainer and I was CCed in fixing the recent fallout from Chris changes as well. Regards, Christian.
> > > Yes, I fixed the original false positive messages myself with the swiotlb > maintainer and I was CCed in fixing the recent fallout from Chris changes as > well. So do we have a good summary of where this at now? I'm getting reports on 4.16.4 still displaying these, what hammer do I need to hit things with to get 4.16.x+1 to not do this? Is there still outstanding issues upstream. For future reference I think how this should have gone down is a) AMD implement a public CI with igt tests for all of this b) we get these patches pushed and debugged. Though to be a bit more constructive, I think you should have said at -rc6 or 7 this isn't working for this kernel cycle, push a minimal patch to back it off, even if the bug is in swiotlb, we don't just add stuff broken like this, even if it's not your bug we should have backed off for a kernel or two until we had the underlying infrastructure fixed. Otherwise we get what we have now, which is bit of a crappile, because now I've no idea if the swiotlb things people report are the false positive, or some new thing. Dave.
On 2018-05-01 01:15 AM, Dave Airlie wrote: >> >> >> Yes, I fixed the original false positive messages myself with the swiotlb >> maintainer and I was CCed in fixing the recent fallout from Chris changes as >> well. > > So do we have a good summary of where this at now? > > I'm getting reports on 4.16.4 still displaying these, what hammer do I > need to hit things with to get 4.16.x+1 to not do this? > > Is there still outstanding issues upstream. There are, https://patchwork.freedesktop.org/patch/219765/ should hopefully fix the last of it. > [...] I've no idea if the swiotlb things people report are the false > positive, or some new thing. The issues I've seen reported with 4.16 are false positives from TTM's perspective, which uses DMA_ATTR_NO_WARN to suppress these warnings, due to multiple regressions introduced by commit 0176adb004065d6815a8e67946752df4cd947c5b "swiotlb: refactor coherent buffer allocation" in 4.16-rc1.
On 2018-04-29 01:56 AM, Ilia Mirkin wrote: > On Sat, Apr 28, 2018 at 7:02 PM, Michel Dänzer <michel@daenzer.net> wrote: >> >> Unfortunately, there was an swiotlb regression (not directly related to >> Christian's work) shortly after this fix, also in 4.16-rc1, which is now >> fixed in 4.17-rc1 and will be backported to 4.16.y. > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=v4.16.5&id=2c9dacf5bfe1e45d96dfe97cb71d2b717786a7b9 > > This guy? Didn't help. I'm running 4.16.4 right now. Try https://patchwork.freedesktop.org/patch/219765/ . >>> We now have *two* broken releases, v4.15 and v4.16 (anything that >>> spews error messages and stack traces ad-infinitum in dmesg is, by >>> definition, broken). >> >> I haven't seen any evidence that there's still an issue in 4.15, is >> there any? > > Well, I did have a late 4.15 rc kernel in addition to the 'suppress > warning' patch. Now I'm questioning my memory of whether the issue was > resolved there or not. I'm pretty sure that 'not', but no longer 100%. It seems pretty clear it is in fact resolved in 4.15. Even if it indeed wasn't for you, did you expect us to find out by monitoring you on IRC 24/7? > As a user who is not in a position to debug this directly due to lack > of time and knowledge, [...] I have plenty of other things to do other than looking into this and coming up with the fix above as well, and I'm no more knowledgeable about the SWIOTLB code than you. Anyway, nobody can track down every problem they run into. But let me kindly ask you to more carefully look at the information available before deciding which tree to bark up in the future.
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index dfd22db13fb1..e03e9e361e2a 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -988,7 +988,7 @@ static struct ttm_tt *amdgpu_ttm_tt_create(struct ttm_buffer_object *bo, return NULL; } gtt->ttm.ttm.func = &amdgpu_backend_func; - if (ttm_sg_tt_init(>t->ttm, bo, page_flags)) { + if (ttm_sg_tt_init(>t->ttm, bo, page_flags | TTM_PAGE_FLAG_TRANSHUGE)) { kfree(gtt); return NULL; } diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c index f0481b7b60c5..476d668e1cbd 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c @@ -760,7 +760,7 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags, { struct ttm_page_pool *pool = ttm_get_pool(flags, false, cstate); #ifdef CONFIG_TRANSPARENT_HUGEPAGE - struct ttm_page_pool *huge = ttm_get_pool(flags, true, cstate); + struct ttm_page_pool *huge = NULL; #endif unsigned long irq_flags; unsigned i; @@ -780,7 +780,8 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags, } #ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (!(flags & TTM_PAGE_FLAG_DMA32)) { + if ((flags & (TTM_PAGE_FLAG_DMA32 | TTM_PAGE_FLAG_TRANSHUGE)) == + TTM_PAGE_FLAG_TRANSHUGE) { for (j = 0; j < HPAGE_PMD_NR; ++j) if (p++ != pages[i + j]) break; @@ -805,6 +806,8 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags, i = 0; #ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (flags & TTM_PAGE_FLAG_TRANSHUGE) + huge = ttm_get_pool(flags, true, cstate); if (huge) { unsigned max_size, n2free; @@ -877,7 +880,7 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags, { struct ttm_page_pool *pool = ttm_get_pool(flags, false, cstate); #ifdef CONFIG_TRANSPARENT_HUGEPAGE - struct ttm_page_pool *huge = ttm_get_pool(flags, true, cstate); + struct ttm_page_pool *huge = NULL; #endif struct list_head plist; struct page *p = NULL; @@ -906,7 +909,8 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags, i = 0; #ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (!(gfp_flags & GFP_DMA32)) { + if ((flags & (TTM_PAGE_FLAG_DMA32 | TTM_PAGE_FLAG_TRANSHUGE)) == + TTM_PAGE_FLAG_TRANSHUGE) { while (npages >= HPAGE_PMD_NR) { gfp_t huge_flags = gfp_flags; @@ -933,9 +937,13 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags, return -ENOMEM; } - /* Swap the pages if we detect consecutive order */ - if (i > first && pages[i - 1] == p - 1) - swap(p, pages[i - 1]); +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (flags & TTM_PAGE_FLAG_TRANSHUGE) { + /* Swap the pages if we detect consecutive order */ + if (i > first && pages[i - 1] == p - 1) + swap(p, pages[i - 1]); + } +#endif pages[i++] = p; --npages; @@ -946,6 +954,8 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags, count = 0; #ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (flags & TTM_PAGE_FLAG_TRANSHUGE) + huge = ttm_get_pool(flags, true, cstate); if (huge && npages >= HPAGE_PMD_NR) { INIT_LIST_HEAD(&plist); ttm_page_pool_get_pages(huge, &plist, flags, cstate, @@ -969,9 +979,14 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags, list_for_each_entry(p, &plist, lru) { struct page *tmp = p; - /* Swap the pages if we detect consecutive order */ - if (count > first && pages[count - 1] == tmp - 1) - swap(tmp, pages[count - 1]); +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (flags & TTM_PAGE_FLAG_TRANSHUGE) { + /* Swap the pages if we detect consecutive order */ + if (count > first && pages[count - 1] == tmp - 1) + swap(tmp, pages[count - 1]); + } +#endif + pages[count++] = tmp; } diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c index 8a25d1974385..291b04213ec5 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c @@ -949,7 +949,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev, type = ttm_to_type(ttm->page_flags, ttm->caching_state); #ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (ttm->page_flags & TTM_PAGE_FLAG_DMA32) + if ((ttm->page_flags & (TTM_PAGE_FLAG_DMA32 | TTM_PAGE_FLAG_TRANSHUGE)) + != TTM_PAGE_FLAG_TRANSHUGE) goto skip_huge; pool = ttm_dma_find_pool(dev, type | IS_HUGE); @@ -1035,7 +1036,7 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev) { struct ttm_tt *ttm = &ttm_dma->ttm; struct ttm_mem_global *mem_glob = ttm->bdev->glob->mem_glob; - struct dma_pool *pool; + struct dma_pool *pool = NULL; struct dma_page *d_page, *next; enum pool_type type; bool is_cached = false; @@ -1045,7 +1046,8 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev) type = ttm_to_type(ttm->page_flags, ttm->caching_state); #ifdef CONFIG_TRANSPARENT_HUGEPAGE - pool = ttm_dma_find_pool(dev, type | IS_HUGE); + if (ttm->page_flags & TTM_PAGE_FLAG_TRANSHUGE) + pool = ttm_dma_find_pool(dev, type | IS_HUGE); if (pool) { count = 0; list_for_each_entry_safe(d_page, next, &ttm_dma->pages_list, diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h index c0e928abf592..c7d2120f0362 100644 --- a/include/drm/ttm/ttm_tt.h +++ b/include/drm/ttm/ttm_tt.h @@ -41,6 +41,7 @@ struct ttm_operation_ctx; #define TTM_PAGE_FLAG_DMA32 (1 << 7) #define TTM_PAGE_FLAG_SG (1 << 8) #define TTM_PAGE_FLAG_NO_RETRY (1 << 9) +#define TTM_PAGE_FLAG_TRANSHUGE (1 << 10) enum ttm_caching_state { tt_uncached,