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Message-ID: <CAJuCfpHovr3NL-v_Cs=eTR9cq73nTuPwwg7cKDQhORmNLwOsrA@mail.gmail.com> Date: Tue, 10 Dec 2024 09:36:42 -0800 From: Suren Baghdasaryan <surenb@...gle.com> To: Hao Ge <hao.ge@...ux.dev> Cc: Ben Greear <greearb@...delatech.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: BISECTED: 'alloc_tag: populate memory for module tags as needed' crashes on boot. On Mon, Dec 9, 2024 at 8:21 PM Hao Ge <hao.ge@...ux.dev> wrote: > > Hi Suren and Ben > > > On 12/10/24 06:33, Suren Baghdasaryan wrote: > > On Mon, Dec 9, 2024 at 4:48 AM Hao Ge <hao.ge@...ux.dev> wrote: > >> Hi Suren > >> > >> > >> On 12/7/24 09:27, Suren Baghdasaryan wrote: > >>> On Fri, Dec 6, 2024 at 4:50 PM Ben Greear <greearb@...delatech.com> wrote: > >>>> On 12/6/24 16:15, Suren Baghdasaryan wrote: > >>>>> On Fri, Dec 6, 2024 at 2:55 PM Suren Baghdasaryan <surenb@...gle.com> wrote: > >>>>>> On Fri, Dec 6, 2024 at 2:43 PM Ben Greear <greearb@...delatech.com> wrote: > >>>>>>> On 12/6/24 14:03, Suren Baghdasaryan wrote: > >>>>>>>> On Fri, Dec 6, 2024 at 1:50 PM Ben Greear <greearb@...delatech.com> wrote: > >>>>>>>>> Hello Suren, > >>>>>>>>> > >>>>>>>>> My system crashes on bootup, and I bisected to this commit. > >>>>>>>>> > >>>>>>>>> 0f9b685626daa2f8e19a9788625c9b624c223e45 is the first bad commit > >>>>>>>>> commit 0f9b685626daa2f8e19a9788625c9b624c223e45 > >>>>>>>>> Author: Suren Baghdasaryan <surenb@...gle.com> > >>>>>>>>> Date: Wed Oct 23 10:07:57 2024 -0700 > >>>>>>>>> > >>>>>>>>> alloc_tag: populate memory for module tags as needed > >>>>>>>>> > >>>>>>>>> The memory reserved for module tags does not need to be backed by physical > >>>>>>>>> pages until there are tags to store there. Change the way we reserve this > >>>>>>>>> memory to allocate only virtual area for the tags and populate it with > >>>>>>>>> physical pages as needed when we load a module. > >>>>>>>>> > >>>>>>>>> The crash looks like this: > >>>>>>>>> > >>>>>>>>> BUG: unable to handle page fault for address: fffffbfff4041000 > >>>>>>>>> #PF: supervisor read access in kernel mode > >>>>>>>>> #PF: error_code(0x0000) - not-present page > >>>>>>>>> PGD 44d0e7067 P4D 44d0e7067 PUD 44d0e3067 PMD 10bb38067 PTE 0 > >>>>>>>>> Oops: Oops: 0000 [#1] PREEMPT SMP KASAN > >>>>>>>>> CPU: 0 UID: 0 PID: 319 Comm: systemd-udevd Not tainted 6.12.0-rc6+ #21 > >>>>>>>>> Hardware name: Default string Default string/SKYBAY, BIOS 5.12 02/15/2023 > >>>>>>>>> RIP: 0010:kasan_check_range+0xa5/0x190 > >>>>>>>>> Code: 8d 5a 07 4c 0f 49 da 49 c1 fb 03 45 85 db 0f 84 ce 00 00 00 45 89 db 4a 8d 14 d8 eb 0d 48 83 c0 08 48 39 d0 0f 84 b29 > >>>>>>>>> RSP: 0018:ffff88812c26f980 EFLAGS: 00010206 > >>>>>>>>> RAX: fffffbfff4041000 RBX: fffffbfff404101e RCX: ffffffff814ec29b > >>>>>>>>> [ OK DX: fffffbfff4041018 RSI: 00000000000000f0 RDI: ffffffffa0208000 > >>>>>>>>> 0m] Finished BP: fffffbfff4041000 R08: 0000000000000001 R09: fffffbfff404101d > >>>>>>>>> ;1;39msystemd-udR10: ffffffffa02080ef R11: 0000000000000003 R12: ffffffffa0208000 > >>>>>>>>> ev-trig…e R13: ffffc90000dac7c8 R14: ffffc90000dac7e8 R15: dffffc0000000000 > >>>>>>>>> - Coldplug All uFS: 00007fe869216b40(0000) GS:ffff88841da00000(0000) knlGS:0000000000000000 > >>>>>>>>> dev Devices. > >>>>>>>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >>>>>>>>> CR2: fffffbfff4041000 CR3: 0000000121e86002 CR4: 00000000003706f0 > >>>>>>>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >>>>>>>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > >>>>>>>>> Call Trace: > >>>>>>>>> <TASK> > >>>>>>>>> [ OK ? __die+0x1f/0x60 > >>>>>>>>> 0m] Reached targ ? page_fault_oops+0x258/0x910 > >>>>>>>>> et sysi ? dump_pagetable+0x690/0x690 > >>>>>>>>> nit.target - ? search_bpf_extables+0x22/0x250 > >>>>>>>>> System Initiali ? trace_page_fault_kernel+0x120/0x120 > >>>>>>>>> zation. > >>>>>>>>> ? search_bpf_extables+0x164/0x250 > >>>>>>>>> ? kasan_check_range+0xa5/0x190 > >>>>>>>>> ? fixup_exception+0x4d/0xc70 > >>>>>>>>> ? exc_page_fault+0xe1/0xf0 > >>>>>>>>> [ OK ? asm_exc_page_fault+0x22/0x30 > >>>>>>>>> 0m] Reached targ ? load_module+0x3d7b/0x7560 > >>>>>>>>> et netw ? kasan_check_range+0xa5/0x190 > >>>>>>>>> ork.target - __asan_memcpy+0x38/0x60 > >>>>>>>>> Network. > >>>>>>>>> load_module+0x3d7b/0x7560 > >>>>>>>>> ? module_frob_arch_sections+0x30/0x30 > >>>>>>>>> ? lockdep_lock+0xbe/0x1b0 > >>>>>>>>> ? rw_verify_area+0x18d/0x5e0 > >>>>>>>>> ? kernel_read_file+0x246/0x870 > >>>>>>>>> ? __x64_sys_fspick+0x290/0x290 > >>>>>>>>> ? init_module_from_file+0xd1/0x130 > >>>>>>>>> init_module_from_file+0xd1/0x130 > >>>>>>>>> ? __ia32_sys_init_module+0xa0/0xa0 > >>>>>>>>> ? lock_acquire+0x2d/0xb0 > >>>>>>>>> ? idempotent_init_module+0x116/0x790 > >>>>>>>>> ? do_raw_spin_unlock+0x54/0x220 > >>>>>>>>> idempotent_init_module+0x226/0x790 > >>>>>>>>> ? init_module_from_file+0x130/0x130 > >>>>>>>>> ? vm_mmap_pgoff+0x203/0x2e0 > >>>>>>>>> __x64_sys_finit_module+0xba/0x130 > >>>>>>>>> do_syscall_64+0x69/0x160 > >>>>>>>>> entry_SYSCALL_64_after_hwframe+0x4b/0x53 > >>>>>>>>> RIP: 0033:0x7fe869de327d > >>>>>>>>> Code: 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 248 > >>>>>>>>> RSP: 002b:00007ffe34a828d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 > >>>>>>>>> RAX: ffffffffffffffda RBX: 0000557fa8f3f3f0 RCX: 00007fe869de327d > >>>>>>>>> RDX: 0000000000000000 RSI: 00007fe869f4943c RDI: 0000000000000006 > >>>>>>>>> RBP: 00007fe869f4943c R08: 0000000000000000 R09: 0000000000000000 > >>>>>>>>> R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000020000 > >>>>>>>>> R13: 0000557fa8f3f030 R14: 0000000000000000 R15: 0000557fa8f3d110 > >>>>>>>>> </TASK> > >>>>>>>>> Modules linked in: > >>>>>>>>> CR2: fffffbfff4041000 > >>>>>>>>> ---[ end trace 0000000000000000 ]--- > >>>>>>>>> > >>>>>>>>> I suspect you only hit this with an unlucky amount of debugging enabled. The kernel config I used > >>>>>>>>> is found here: > >>>>>>>>> > >>>>>>>>> http://www.candelatech.com/downloads/cfg-kasan-crash-regression.config > >>>>>>>>> > >>>>>>>>> I will be happy to test fixes. > >>>>>>>> Hi Ben, > >>>>>>>> Thanks for reporting the issue. Do you have these recent fixes in your tree: > >>>>>>>> > >>>>>>>> https://lore.kernel.org/all/20241130001423.1114965-1-surenb@google.com/ > >>>>>>>> https://lore.kernel.org/all/20241205170528.81000-1-hao.ge@linux.dev/ > >>>>>>>> > >>>>>>>> If not, couple you please apply them and see if the issue is still happening? > >>>>>>>> Thanks, > >>>>>>>> Suren. > >>>>>>> Hello Suren, > >>>>>>> > >>>>>>> Thanks for the quick response. The first patch is already in latest Linus tree, > >>>>> Hmm. Could you please double-check which tree you are using? I don't > >>>>> see the first patch > >>>>> (https://lore.kernel.org/all/20241130001423.1114965-1-surenb@google.com/) > >>>>> in Linus' tree. Maybe you are using linux-next? > >>>> Sorry, you are correct. I must have mangled something when trying to apply > >>>> the patch and I didn't look hard enough when patch said changes were already applied. > >>>> > >>>> I can re-test this next week...and for reference, kernel boots fine when you disable > >>>> KASAN and other debugging. > >>> Thanks! Please retest with this patch and let me know if you are still > >>> having issues. > >>> Suren. > >> Indeed, this is a bug that still exists in another context, namely when > >> CONFIG_KASAN_VMALLOC is not enabled. > > Hmm. Are you able to reproduce this issue with all the fixes we had? > > > Yes, I set up an x86 virtual machine and after porting both of our > patches, I encountered a reproduction of the issue. > > I have also submitted a patch to fix this issue. > > https://lore.kernel.org/all/20241210041515.765569-1-hao.ge@linux.dev/ Thanks! I'll post my comments there. > > I verified it locally. > > > Hi Ben > > Can you test with this patch? > > > Thanks > > Best Regards > > Hao > > > > >> We may need to look into this scenario next. > >> > >> Thanks > >> > >> Best Regards > >> > >> Hao > >> > >>>> Thanks, > >>>> Ben > >>>> > >>>> > >>>> -- > >>>> Ben Greear <greearb@...delatech.com> > >>>> Candela Technologies Inc http://www.candelatech.com > >>>> > >>>>
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