Em Mon, 18 Oct 2021 01:23:33 +0900 Tsuchiya Yuto <kitakar@xxxxxxxxx> escreveu: > This is almost a BUG report with a patch to just avoid kernel error > message. Thus, prefixed with [BUG][RFC]. > > RFC: > 1. Regarding the NULL check in hmm_init(), it was added for the case > when probe failed [1]. So, need to address that case with the other > means? But I'm not sure how we can do for the case. > 2. Regarding the WARN_ON() in hmm_free(), there is a patch from Alan > ("atomisp: hmm gives a bogus warning on unload") [1] but I haven't > looked into it yet. > > [1] https://lore.kernel.org/linux-media/151001141201.77201.10725942741811192730.stgit@alans-desktop/ > > >8-----------------------------------------------------------------8< > > The NULL check for dummy_ptr in hmm_init() [1] results in the following > "hmm_init Failed to create sysfs" error exactly once every > two times on atomisp reload by rmmod/insmod (although atomisp module > loads and works fine regardless of this error): > > kern :warn : [ 140.230662] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:03.0/active_bo' > kern :warn : [ 140.230668] CPU: 1 PID: 2502 Comm: insmod Tainted: G C OE 5.15.0-rc4-1-surface-mainline #1 b8acf6eb64994414b2e20bad312a7a2c45f748f9 > kern :warn : [ 140.230675] Hardware name: OEMB OEMB/OEMB, BIOS 1.51116.238 03/09/2015 > kern :warn : [ 140.230678] Call Trace: > kern :warn : [ 140.230687] dump_stack_lvl+0x46/0x5a > kern :warn : [ 140.230702] sysfs_warn_dup.cold+0x17/0x24 > kern :warn : [ 140.230710] sysfs_add_file_mode_ns+0x160/0x170 > kern :warn : [ 140.230717] internal_create_group+0x126/0x390 > kern :warn : [ 140.230723] hmm_init+0x5c/0x70 [atomisp 7a6a680bf400629363d2a6f58fd10e7299678b99] > kern :warn : [ 140.230811] atomisp_pci_probe.cold+0x1136/0x148e [atomisp 7a6a680bf400629363d2a6f58fd10e7299678b99] > kern :warn : [ 140.230875] local_pci_probe+0x45/0x80 > kern :warn : [ 140.230882] ? pci_match_device+0xd7/0x130 > kern :warn : [ 140.230887] pci_device_probe+0xfa/0x1b0 > kern :warn : [ 140.230892] really_probe+0x1f5/0x3f0 > kern :warn : [ 140.230899] __driver_probe_device+0xfe/0x180 > kern :warn : [ 140.230903] driver_probe_device+0x1e/0x90 > kern :warn : [ 140.230908] __driver_attach+0xc0/0x1c0 > kern :warn : [ 140.230912] ? __device_attach_driver+0xe0/0xe0 > kern :warn : [ 140.230915] ? __device_attach_driver+0xe0/0xe0 > kern :warn : [ 140.230919] bus_for_each_dev+0x89/0xd0 > kern :warn : [ 140.230924] bus_add_driver+0x12b/0x1e0 > kern :warn : [ 140.230929] driver_register+0x8f/0xe0 > kern :warn : [ 140.230933] ? 0xffffffffc153f000 > kern :warn : [ 140.230937] do_one_initcall+0x57/0x220 > kern :warn : [ 140.230945] do_init_module+0x5c/0x260 > kern :warn : [ 140.230952] load_module+0x24bd/0x26a0 > kern :warn : [ 140.230962] ? __do_sys_finit_module+0xae/0x110 > kern :warn : [ 140.230966] __do_sys_finit_module+0xae/0x110 > kern :warn : [ 140.230972] do_syscall_64+0x5c/0x80 > kern :warn : [ 140.230979] ? syscall_exit_to_user_mode+0x23/0x40 > kern :warn : [ 140.230983] ? do_syscall_64+0x69/0x80 > kern :warn : [ 140.230988] ? exc_page_fault+0x72/0x170 > kern :warn : [ 140.230991] entry_SYSCALL_64_after_hwframe+0x44/0xae > kern :warn : [ 140.230997] RIP: 0033:0x7f7fd5d8718d > kern :warn : [ 140.231003] Code: b4 0c 00 0f 05 eb a9 66 0f 1f 44 00 00 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 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b3 6c 0c 00 f7 d8 64 89 01 48 > kern :warn : [ 140.231006] RSP: 002b:00007ffefc25f0e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 > kern :warn : [ 140.231012] RAX: ffffffffffffffda RBX: 000055ac3edcd7f0 RCX: 00007f7fd5d8718d > kern :warn : [ 140.231015] RDX: 0000000000000000 RSI: 000055ac3d723270 RDI: 0000000000000003 > kern :warn : [ 140.231017] RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f7fd5e52380 > kern :warn : [ 140.231019] R10: 0000000000000003 R11: 0000000000000246 R12: 000055ac3d723270 > kern :warn : [ 140.231021] R13: 0000000000000000 R14: 000055ac3edd06e0 R15: 0000000000000000 > kern :err : [ 140.231038] atomisp-isp2 0000:00:03.0: hmm_init Failed to create sysfs > > So, remove the NULL check to always call sysfs_remove_group() and fix > the above error. > > At this point, atomisp now gives WARN_ON() in hmm_free() [2] on atomisp > reload by rmmod/insmod. So, also remove it. > > [1] added on commit > d9ab83953fa7 ("media: atomisp: don't cause a warn if probe failed") > [2] added on commit > b83cc378dfc4 ("atomisp: clean up the hmm init/cleanup indirections") Interesting bug. As dummy_ptr == 0 is indeed a valid value, and the driver should not call sysfs_remove_group() if sysfs_create_group(), the right fix seem to use mmgr_EXCEPTION as the default value for dummy_ptr. This way, the check before calling sys group removal logic will still preserved. On other words: @@ -39,7 +39,7 @@ struct hmm_bo_device bo_device; struct hmm_pool dynamic_pool; struct hmm_pool reserved_pool; -static ia_css_ptr dummy_ptr; +static ia_css_ptr dummy_ptr = mmgr_EXCEPTION; static bool hmm_initialized; struct _hmm_mem_stat hmm_mem_stat; @@ -209,7 +209,7 @@ int hmm_init(void) void hmm_cleanup(void) { - if (!dummy_ptr) + if (dummy_ptr == mmgr_EXCEPTION) return; sysfs_remove_group(&atomisp_dev->kobj, atomisp_attribute_group); The WARN_ON(!virt) should be removed anyway, as virt == 0 is a valid value. I'll do the above changes and apply the patch. > > Signed-off-by: Tsuchiya Yuto <kitakar@xxxxxxxxx> > --- > drivers/staging/media/atomisp/pci/hmm/hmm.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/drivers/staging/media/atomisp/pci/hmm/hmm.c b/drivers/staging/media/atomisp/pci/hmm/hmm.c > index 6a5ee4607089..47dc3df3b800 100644 > --- a/drivers/staging/media/atomisp/pci/hmm/hmm.c > +++ b/drivers/staging/media/atomisp/pci/hmm/hmm.c > @@ -209,8 +209,6 @@ int hmm_init(void) > > void hmm_cleanup(void) > { > - if (!dummy_ptr) > - return; > sysfs_remove_group(&atomisp_dev->kobj, atomisp_attribute_group); > > /* free dummy memory first */ > @@ -288,8 +286,6 @@ void hmm_free(ia_css_ptr virt) > > dev_dbg(atomisp_dev, "%s: free 0x%08x\n", __func__, virt); > > - WARN_ON(!virt); > - > bo = hmm_bo_device_search_start(&bo_device, (unsigned int)virt); > > if (!bo) {