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Message-ID: <a692d5d7-11d5-4c1b-9abc-208d2194ccde@alu.unizg.hr> Date: Sat, 23 Mar 2024 21:13:01 +0100 From: Mirsad Todorovac <mirsad.todorovac@....unizg.hr> To: Jason Gunthorpe <jgg@...dia.com> Cc: iommu@...ts.linux.dev, Kevin Tian <kevin.tian@...el.com>, Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [BUG] seltests/iommu: runaway ./iommufd consuming 99% CPU after a failed assert() On 3/19/24 14:58, Jason Gunthorpe wrote: > On Tue, Mar 12, 2024 at 07:35:40AM +0100, Mirsad Todorovac wrote: >> Hi, >> >> (This is verified on the second test box.) >> >> In the most recent 6.8.0 release of torvalds tree kernel with selftest configs on, >> process ./iommufd appears to consume 99% of a CPU core for quote a while in an >> endless loop: > > There is a "bug" in the ksefltest framework where if you call a > kselftest assertion from the setup/teardown it infinite loops > > The fix I know is to replace kselftest assertions with normal assert() > > But I don't see an obvious thing here saying you are hitting that.. > > Jason Hi, I'm not that deep into kselftest for that intervention. Yet, with the v6.8-11743-ga4145ce1e7bc build, the problem with ./iommufd did not stuck. Instead I got these 10 failed tests: # # RUN iommufd_dirty_tracking.domain_dirty128M_huge.enforce_dirty ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # enforce_dirty: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty128M_huge.enforce_dirty # not ok 156 iommufd_dirty_tracking.domain_dirty128M_huge.enforce_dirty # # RUN iommufd_dirty_tracking.domain_dirty128M_huge.set_dirty_tracking ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # set_dirty_tracking: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty128M_huge.set_dirty_tracking # not ok 157 iommufd_dirty_tracking.domain_dirty128M_huge.set_dirty_tracking # # RUN iommufd_dirty_tracking.domain_dirty128M_huge.device_dirty_capability ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # device_dirty_capability: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty128M_huge.device_dirty_capability # not ok 158 iommufd_dirty_tracking.domain_dirty128M_huge.device_dirty_capability # # RUN iommufd_dirty_tracking.domain_dirty128M_huge.get_dirty_bitmap ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # get_dirty_bitmap: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty128M_huge.get_dirty_bitmap # not ok 159 iommufd_dirty_tracking.domain_dirty128M_huge.get_dirty_bitmap # # RUN iommufd_dirty_tracking.domain_dirty128M_huge.get_dirty_bitmap_no_clear ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # get_dirty_bitmap_no_clear: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty128M_huge.get_dirty_bitmap_no_clear # not ok 160 iommufd_dirty_tracking.domain_dirty128M_huge.get_dirty_bitmap_no_clear . . . # # RUN iommufd_dirty_tracking.domain_dirty256M_huge.enforce_dirty ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # enforce_dirty: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty256M_huge.enforce_dirty # not ok 166 iommufd_dirty_tracking.domain_dirty256M_huge.enforce_dirty # # RUN iommufd_dirty_tracking.domain_dirty256M_huge.set_dirty_tracking ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # set_dirty_tracking: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty256M_huge.set_dirty_tracking # not ok 167 iommufd_dirty_tracking.domain_dirty256M_huge.set_dirty_tracking # # RUN iommufd_dirty_tracking.domain_dirty256M_huge.device_dirty_capability ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # device_dirty_capability: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty256M_huge.device_dirty_capability # not ok 168 iommufd_dirty_tracking.domain_dirty256M_huge.device_dirty_capability # # RUN iommufd_dirty_tracking.domain_dirty256M_huge.get_dirty_bitmap ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # get_dirty_bitmap: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty256M_huge.get_dirty_bitmap # not ok 169 iommufd_dirty_tracking.domain_dirty256M_huge.get_dirty_bitmap # # RUN iommufd_dirty_tracking.domain_dirty256M_huge.get_dirty_bitmap_no_clear ... # iommufd: iommufd.c:1749: iommufd_dirty_tracking_setup: Assertion `vrc == self->buffer' failed. # # get_dirty_bitmap_no_clear: Test terminated by assertion # # FAIL iommufd_dirty_tracking.domain_dirty256M_huge.get_dirty_bitmap_no_clear # not ok 170 iommufd_dirty_tracking.domain_dirty256M_huge.get_dirty_bitmap_no_clear . . . # # FAILED: 170 / 180 tests passed. # # Totals: pass:170 fail:10 xfail:0 xpass:0 skip:0 error:0 not ok 1 selftests: iommu: iommufd # exit=1 It seems like the same assertion failed in all 10 failed tests? However, I am not smart enough to figure out why ... Apparently, from the source, mmap() fails to allocate pages on the desired address: 1746 assert((uintptr_t)self->buffer % HUGEPAGE_SIZE == 0); 1747 vrc = mmap(self->buffer, variant->buffer_size, PROT_READ | PROT_WRITE, 1748 mmap_flags, -1, 0); → 1749 assert(vrc == self->buffer); 1750 But I am not that deep into the source to figure our what was intended and what went wrong :-/ Best regards, Mirsad Todorovac
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