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Date: Mon, 17 Mar 2014 17:43:58 +0300
From: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To: Minchan Kim <minchan@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Nitin Gupta <ngupta@...are.org>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Jerome Marchand <jmarchan@...hat.com>,
linux-kernel@...r.kernel.org
Subject: zram: zsmalloc calls sleeping function from atomic context
Hello gents,
I just noticed that starting from commit
commit 3d693a5127e79e79da7c34dc0c776bc620697ce5
Author: Andrew Morton <akpm@...ux-foundation.org>
Date: Mon Mar 17 11:23:56 2014 +1100
mm-vmalloc-avoid-soft-lockup-warnings-when-vunmaping-large-ranges-fix
add a might_sleep() to catch atomic callers more promptly
and
commit 032dda8b6c4021d4be63bcc483b47fd26c6f48a2
Author: David Vrabel <david.vrabel@...rix.com>
Date: Mon Mar 17 11:23:56 2014 +1100
mm/vmalloc: avoid soft lockup warnings when vunmap()'ing large ranges
If vunmap() is used to unmap a large (e.g., 50 GB) region, it may take
sufficiently long that it triggers soft lockup warnings.
Add a cond_resched() into vunmap_pmd_range() so the calling task may be
resheduled after unmapping each PMD entry. This is how zap_pmd_range()
fixes the same problem for userspace mappings.
All callers may sleep except for the APEI GHES driver (apei/ghes.c) which
calls unmap_kernel_range_no_flush() from NMI and IRQ contexts. This
driver only unmaps a single pages so don't call cond_resched() if the
unmap doesn't cross a PMD boundary.
w/ CONFIG_PGTABLE_MAPPING=y zs_unmap_object() calls unmap_kernel_range() under rwlock,
producing the following warning (basically we perform every read()/write() under
rwlock, so I can see lots of these warnings):
[ 631.541177] BUG: sleeping function called from invalid context at mm/vmalloc.c:74
[ 631.541181] in_atomic(): 1, irqs_disabled(): 0, pid: 94, name: kworker/u8:2
[ 631.541183] Preemption disabled at:[<ffffffffa00ca0ad>] zram_bvec_rw.isra.14+0x2be/0x4fc [zram]
[ 631.541193] CPU: 2 PID: 94 Comm: kworker/u8:2 Tainted: G O 3.14.0-rc6-next-20140317-dbg-dirty #182
[ 631.541195] Hardware name: Acer Aspire 5741G /Aspire 5741G , BIOS V1.20 02/08/2011
[ 631.541202] Workqueue: writeback bdi_writeback_workfn (flush-254:0)
[ 631.541205] 0000000000000000 ffff88015211b748 ffffffff813ba01d 0000000000000000
[ 631.541208] ffff88015211b768 ffffffff81057ecb ffffc9000003e000 ffffc9000003e000
[ 631.541212] ffff88015211b7d8 ffffffff810cc491 ffffc9000003dfff ffff88015211b800
[ 631.541216] Call Trace:
[ 631.541223] [<ffffffff813ba01d>] dump_stack+0x4e/0x7a
[ 631.541229] [<ffffffff81057ecb>] __might_sleep+0x14e/0x153
[ 631.541234] [<ffffffff810cc491>] vunmap_page_range+0x133/0x25d
[ 631.541237] [<ffffffff810cd81b>] unmap_kernel_range+0x16/0x26
[ 631.541241] [<ffffffff810de6f6>] zs_unmap_object+0xd8/0xff
[ 631.541245] [<ffffffffa00ca120>] zram_bvec_rw.isra.14+0x331/0x4fc [zram]
[ 631.541248] [<ffffffffa00ca439>] zram_make_request+0x14e/0x228 [zram]
[ 631.541252] [<ffffffff810a8088>] ? mempool_alloc+0x6d/0x130
[ 631.541257] [<ffffffff811e9395>] generic_make_request+0x97/0xd6
[ 631.541259] [<ffffffff811e94c6>] submit_bio+0xf2/0x131
[ 631.541263] [<ffffffff81106306>] _submit_bh+0x1c1/0x1eb
[ 631.541266] [<ffffffff8110633b>] submit_bh+0xb/0xd
[ 631.541269] [<ffffffff811078d9>] __block_write_full_page+0x1ad/0x2c8
[ 631.541273] [<ffffffff8110a118>] ? I_BDEV+0xd/0xd
[ 631.541276] [<ffffffff81105041>] ? end_buffer_write_sync+0x61/0x61
[ 631.541278] [<ffffffff8110a118>] ? I_BDEV+0xd/0xd
[ 631.541282] [<ffffffff81107bb4>] block_write_full_page_endio+0xdc/0xe8
[ 631.541284] [<ffffffff81107bd0>] block_write_full_page+0x10/0x12
[ 631.541287] [<ffffffff8110a6e5>] blkdev_writepage+0x13/0x15
[ 631.541292] [<ffffffff810acfb8>] __writepage+0xe/0x2c
[ 631.541295] [<ffffffff810ad35f>] write_cache_pages+0x25c/0x367
[ 631.541297] [<ffffffff810acfaa>] ? mapping_tagged+0xf/0xf
[ 631.541301] [<ffffffff810ad4a3>] generic_writepages+0x39/0x51
[ 631.541304] [<ffffffff810ae6d4>] do_writepages+0x19/0x27
[ 631.541307] [<ffffffff810ff6d4>] __writeback_single_inode+0x3c/0xee
[ 631.541310] [<ffffffff811000d7>] writeback_sb_inodes+0x1bf/0x2f9
[ 631.541313] [<ffffffff8110028b>] __writeback_inodes_wb+0x7a/0xb0
[ 631.541316] [<ffffffff811003c0>] wb_writeback+0xff/0x190
[ 631.541319] [<ffffffff810595f3>] ? get_parent_ip+0xd/0x3c
[ 631.541322] [<ffffffff811008f5>] bdi_writeback_workfn+0xcd/0x28d
[ 631.541325] [<ffffffff8105b32b>] ? try_to_wake_up+0x1f4/0x203
[ 631.541330] [<ffffffff8104d213>] process_one_work+0x1c9/0x2e9
[ 631.541332] [<ffffffff8104d7ad>] worker_thread+0x1d3/0x2bd
[ 631.541335] [<ffffffff8104d5da>] ? rescuer_thread+0x27d/0x27d
[ 631.541338] [<ffffffff81051e75>] kthread+0xd6/0xde
[ 631.541341] [<ffffffff81051d9f>] ? kthread_create_on_node+0x162/0x162
[ 631.541345] [<ffffffff813bf8bc>] ret_from_fork+0x7c/0xb0
[ 631.541348] [<ffffffff81051d9f>] ? kthread_create_on_node+0x162/0x162
-ss
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