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Message-ID: <1320916025-20264-1-git-send-email-linus.walleij@stericsson.com> Date: Thu, 10 Nov 2011 10:07:05 +0100 From: Linus Walleij <linus.walleij@...ricsson.com> To: Andrew Morton <akpm@...ux-foundation.org>, Jens Axboe <jaxboe@...ionio.com> Cc: <linux-kernel@...r.kernel.org>, Rabin Vincent <rabin.vincent@...ricsson.com>, <stable@...nel.org>, Linus Walleij <linus.walleij@...aro.org> Subject: [PATCH] backing-dev: ensure wakeup_timer is deleted From: Rabin Vincent <rabin.vincent@...ricsson.com> bdi_prune_sb() in bdi_unregister() attempts to removes the bdi links from all super_blocks and then del_timer_sync() the writeback timer. However, this can race with __mark_inode_dirty(), leading to bdi_wakeup_thread_delayed() rearming the writeback timer on the bdi we're unregistering, after we've called del_timer_sync(). This can end up with the bdi being freed with an active timer inside it, as in the case of the following dump after the removal of an SD card. Fix this by redoing the del_timer_sync() in bdi_destory(). ------------[ cut here ]------------ WARNING: at /home/rabin/kernel/arm/lib/debugobjects.c:262 debug_print_object+0x9c/0xc8() ODEBUG: free active (active state 0) object type: timer_list hint: wakeup_timer_fn+0x0/0x180 Modules linked in: Backtrace: [<c00109dc>] (dump_backtrace+0x0/0x110) from [<c0236e4c>] (dump_stack+0x18/0x1c) r6:c02bc638 r5:00000106 r4:c79f5d18 r3:00000000 [<c0236e34>] (dump_stack+0x0/0x1c) from [<c0025e6c>] (warn_slowpath_common+0x54/0x6c) [<c0025e18>] (warn_slowpath_common+0x0/0x6c) from [<c0025f28>] (warn_slowpath_fmt+0x38/0x40) r8:20000013 r7:c780c6f0 r6:c031613c r5:c780c6f0 r4:c02b1b29 r3:00000009 [<c0025ef0>] (warn_slowpath_fmt+0x0/0x40) from [<c015eb4c>] (debug_print_object+0x9c/0xc8) r3:c02b1b29 r2:c02bc662 [<c015eab0>] (debug_print_object+0x0/0xc8) from [<c015f574>] (debug_check_no_obj_freed+0xac/0x1dc) r6:c7964000 r5:00000001 r4:c7964000 [<c015f4c8>] (debug_check_no_obj_freed+0x0/0x1dc) from [<c00a9e38>] (kmem_cache_free+0x88/0x1f8) [<c00a9db0>] (kmem_cache_free+0x0/0x1f8) from [<c014286c>] (blk_release_queue+0x70/0x78) [<c01427fc>] (blk_release_queue+0x0/0x78) from [<c015290c>] (kobject_release+0x70/0x84) r5:c79641f0 r4:c796420c [<c015289c>] (kobject_release+0x0/0x84) from [<c0153ce4>] (kref_put+0x68/0x80) r7:00000083 r6:c74083d0 r5:c015289c r4:c796420c [<c0153c7c>] (kref_put+0x0/0x80) from [<c01527d0>] (kobject_put+0x48/0x5c) r5:c79643b4 r4:c79641f0 [<c0152788>] (kobject_put+0x0/0x5c) from [<c013ddd8>] (blk_cleanup_queue+0x68/0x74) r4:c7964000 [<c013dd70>] (blk_cleanup_queue+0x0/0x74) from [<c01a6370>] (mmc_blk_put+0x78/0xe8) r5:00000000 r4:c794c400 [<c01a62f8>] (mmc_blk_put+0x0/0xe8) from [<c01a64b4>] (mmc_blk_release+0x24/0x38) r5:c794c400 r4:c0322824 [<c01a6490>] (mmc_blk_release+0x0/0x38) from [<c00de11c>] (__blkdev_put+0xe8/0x170) r5:c78d5e00 r4:c74083c0 [<c00de034>] (__blkdev_put+0x0/0x170) from [<c00de2c0>] (blkdev_put+0x11c/0x12c) r8:c79f5f70 r7:00000001 r6:c74083d0 r5:00000083 r4:c74083c0 r3:00000000 [<c00de1a4>] (blkdev_put+0x0/0x12c) from [<c00b0724>] (kill_block_super+0x60/0x6c) r7:c7942300 r6:c79f4000 r5:00000083 r4:c74083c0 [<c00b06c4>] (kill_block_super+0x0/0x6c) from [<c00b0a94>] (deactivate_locked_super+0x44/0x70) r6:c79f4000 r5:c031af64 r4:c794dc00 r3:c00b06c4 [<c00b0a50>] (deactivate_locked_super+0x0/0x70) from [<c00b1358>] (deactivate_super+0x6c/0x70) r5:c794dc00 r4:c794dc00 [<c00b12ec>] (deactivate_super+0x0/0x70) from [<c00c88b0>] (mntput_no_expire+0x188/0x194) r5:c794dc00 r4:c7942300 [<c00c8728>] (mntput_no_expire+0x0/0x194) from [<c00c95e0>] (sys_umount+0x2e4/0x310) r6:c7942300 r5:00000000 r4:00000000 r3:00000000 [<c00c92fc>] (sys_umount+0x0/0x310) from [<c000d940>] (ret_fast_syscall+0x0/0x30) ---[ end trace e5c83c92ada51c76 ]--- Cc: stable@...nel.org Signed-off-by: Rabin Vincent <rabin.vincent@...ricsson.com> Signed-off-by: Linus Walleij <linus.walleij@...aro.org> --- mm/backing-dev.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index a086064..71034f4 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -724,6 +724,14 @@ void bdi_destroy(struct backing_dev_info *bdi) bdi_unregister(bdi); + /* + * If bdi_unregister() had already been called earlier, the + * wakeup_timer could still be armed because bdi_prune_sb() + * can race with the bdi_wakeup_thread_delayed() calls from + * __mark_inode_dirty(). + */ + del_timer_sync(&bdi->wb.wakeup_timer); + for (i = 0; i < NR_BDI_STAT_ITEMS; i++) percpu_counter_destroy(&bdi->bdi_stat[i]); -- 1.7.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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