The patch titled i82875p_edac: fix module remove has been added to the -mm tree. Its filename is i82875p_edac-fix-module-remove.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: i82875p_edac: fix module remove From: Jarkko Lavinen <jlavi@xxxxxx> Fix module removal bugs of i82875p_edac. Also i82975x_edac code seems to have the same module removal bugs as in i82875p_edac. The problems were: 1. In module removal i82875p_remove_one() is never called. Variable i82875p_registered is newer changed from 1, which guarantees i82875p_remove_one() is not called (and even if it were called, it would be called in wrong order). As a result, the edac_mc workque is not stopped and keeps probing. If kernel debugging options are not enabled, user may not notice anything going wrong. if debugging options are enabled and I do "rmmod i82875p_edac", I get: edac debug: edac_pci_workq_function() checking BUG: unable to handle kernel paging request at f882d16f ... call trace: [<f8834df3>] ? edac_mc_workq_function+0x55/0x7e [edac_core] [<c0233974>] ? run_workqueue+0xd7/0x1a5 [<c023392f>] ? run_workqueue+0x92/0x1a5 [<f8834d9e>] ? edac_mc_workq_function+0x0/0x7e [edac_core] [<c0233af9>] ? worker_thread+0xb7/0xc3 [<c0236a7b>] ? autoremove_wake_function+0x0/0x33 [<c0233a42>] ? worker_thread+0x0/0xc3 [<c0236809>] ? kthread+0x3b/0x61 [<c02367ce>] ? kthread+0x0/0x61 [<c0204587>] ? kernel_thread_helper+0x7/0x10 Fix for this is to get rid of needles variable i82875p_registered altogether and run i82875p_remove_one() *before* pci_unregister_driver(). 2. edac_mc_del_mc() uses mci after freeing mci edac_mc_del_mc() calls calls edac_remove_sysfs_mci_device(). The kobject refcount of mci drops to 0 and mci is freed. After this mci is accessed via debug print and i82875p_remove_one() still uses mci->pvt and tries to free mci again with edac_mc_free(). The fix for this is add kobject_get(&mci->edac_mci_kobj) after edac_mc_alloc(). Then the mci is still available after returning from edac_mc_del_mc() with refcount 1, and mci->pvt is still available. When i82875p_remove_one() finally calls edac_mc_free(), this will cause kobject_put() and mci is released properly. Signed-off-by: Jarkko Lavinen <jlavi@xxxxxx> Cc: Doug Thompson <norsk5@xxxxxxxxx> Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/edac/i82875p_edac.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff -puN drivers/edac/i82875p_edac.c~i82875p_edac-fix-module-remove drivers/edac/i82875p_edac.c --- a/drivers/edac/i82875p_edac.c~i82875p_edac-fix-module-remove +++ a/drivers/edac/i82875p_edac.c @@ -182,8 +182,6 @@ static struct pci_dev *mci_pdev; /* init * already registered driver */ -static int i82875p_registered = 1; - static struct edac_pci_ctl_info *i82875p_pci; static void i82875p_get_error_info(struct mem_ctl_info *mci, @@ -410,6 +408,9 @@ static int i82875p_probe1(struct pci_dev goto fail0; } + /* Keeps mci available after edac_mc_del_mc() till edac_mc_free() */ + kobject_get(&mci->edac_mci_kobj); + debugf3("%s(): init mci\n", __func__); mci->dev = &pdev->dev; mci->mtype_cap = MEM_FLAG_DDR; @@ -452,6 +453,7 @@ static int i82875p_probe1(struct pci_dev return 0; fail1: + kobject_put(&mci->edac_mci_kobj); edac_mc_free(mci); fail0: @@ -579,12 +581,11 @@ static void __exit i82875p_exit(void) { debugf3("%s()\n", __func__); + i82875p_remove_one(mci_pdev); + pci_dev_put(mci_pdev); + pci_unregister_driver(&i82875p_driver); - if (!i82875p_registered) { - i82875p_remove_one(mci_pdev); - pci_dev_put(mci_pdev); - } } module_init(i82875p_init); _ Patches currently in -mm which might be from jlavi@xxxxxx are i82875p_edac-fix-overflow-device-resource-setup.patch i82875p_edac-fix-module-remove.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html