Re: [PATCH] Repeated fork() causes SLAB to grow without bound

From: Konstantin Khlebnikov
Date: Tue Nov 25 2014 - 07:13:25 EST

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On Tue, Nov 25, 2014 at 1:59 PM, Michal Hocko <mhocko@xxxxxxx> wrote:
> On Mon 24-11-14 11:09:40, Konstantin Khlebnikov wrote:
>> On Thu, Nov 20, 2014 at 6:03 PM, Konstantin Khlebnikov <koct9i@xxxxxxxxx> wrote:
>> > On Thu, Nov 20, 2014 at 5:50 PM, Rik van Riel <riel@xxxxxxxxxx> wrote:
>> >> -----BEGIN PGP SIGNED MESSAGE-----
>> >> Hash: SHA1
>> >>
>> >> On 11/20/2014 09:42 AM, Konstantin Khlebnikov wrote:
>> >>
>> >>> I'm thinking about limitation for reusing anon_vmas which might
>> >>> increase performance without breaking asymptotic estimation of
>> >>> count anon_vma in the worst case. For example this heuristic: allow
>> >>> to reuse only anon_vma with single direct descendant. It seems
>> >>> there will be arount up to two times more anon_vmas but
>> >>> false-aliasing must be much lower.
>>
>> Done. RFC patch in attachment.
>
> This is triggering BUG_ON(anon_vma->degree); in unlink_anon_vmas. I have
> applied the patch on top of 3.18.0-rc6.

It seems I've screwed up with counter if anon_vma is merged in anon_vma_prepare.
Increment must be in the next if block:

--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -182,8 +182,6 @@ int anon_vma_prepare(struct vm_area_struct *vma)
if (unlikely(!anon_vma))
goto out_enomem_free_avc;
allocated = anon_vma;
- /* Bump degree, root anon_vma is its own parent. */
- anon_vma->degree++;
}

anon_vma_lock_write(anon_vma);
@@ -192,6 +190,7 @@ int anon_vma_prepare(struct vm_area_struct *vma)
if (likely(!vma->anon_vma)) {
vma->anon_vma = anon_vma;
anon_vma_chain_link(vma, avc, anon_vma);
+ anon_vma->degree++;
allocated = NULL;
avc = NULL;
}

I've tested it with trinity but probably isn't long enough.

>
> [ 12.380189] ------------[ cut here ]------------
> [ 12.380221] kernel BUG at mm/rmap.c:385!
> [ 12.380239] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> [ 12.380272] Modules linked in: i915 cfbfillrect cfbimgblt i2c_algo_bit fbcon bitblit softcursor cfbcopyarea font drm_kms_helper drm fb fbdev binfmt_misc fuse uvcvideo videobuf2_vmalloc videobuf2_memops arc4 videobuf2_core v4l2_common sdhci_pci iwldvm videodev media mac80211 i2c_i801 i2c_core sdhci mmc_core iwlwifi cfg80211 snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_pcm_oss snd_mixer_oss snd_pcm video backlight snd_timer snd
> [ 12.380518] CPU: 1 PID: 3704 Comm: kdm_greet Not tainted 3.18.0-rc6-test-00001-gf5bc00c103ff #409
> [ 12.380554] Hardware name: Dell Inc. Latitude E6320/09PHH9, BIOS A08 10/18/2011
> [ 12.380584] task: ffff8801272bc2c0 ti: ffff8800bcaf0000 task.ti: ffff8800bcaf0000
> [ 12.380614] RIP: 0010:[<ffffffff81125f09>] [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 12.380653] RSP: 0018:ffff8800bcaf3d28 EFLAGS: 00010286
> [ 12.380676] RAX: ffff8800bcb3e690 RBX: ffff8800bcb35e28 RCX: ffff8801272bcb60
> [ 12.380706] RDX: ffff8800bcb38e70 RSI: 0000000000000001 RDI: ffff8800bcb38e70
> [ 12.380734] RBP: ffff8800bcaf3d78 R08: 0000000000000000 R09: 0000000000000000
> [ 12.380764] R10: 0000000000000000 R11: ffff8800bcb3e6a0 R12: ffff8800bcb3e680
> [ 12.380793] R13: ffff8800bcb3e690 R14: ffff8800bcb38e70 R15: ffff8800bcb38e70
> [ 12.380822] FS: 0000000000000000(0000) GS:ffff88012d440000(0000) knlGS:0000000000000000
> [ 12.380855] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 12.380880] CR2: 00007fcd2603b0e8 CR3: 0000000001a11000 CR4: 00000000000407e0
> [ 12.380908] Stack:
> [ 12.380918] ffff8801272e9dc0 ffff8800bcb35e38 ffff8800bcb35e38 ffff8800bcb3e680
> [ 12.380953] ffff8800bcaf3d78 ffff8800bcb35dc0 ffff8800bcaf3dd8 0000000000000000
> [ 12.380989] 0000000000000000 ffff8800bcb35dc0 ffff8800bcaf3dc8 ffffffff81119e26
> [ 12.381024] Call Trace:
> [ 12.381038] [<ffffffff81119e26>] free_pgtables+0x8e/0xcc
> [ 12.381062] [<ffffffff81121ac1>] exit_mmap+0x84/0x123
> [ 12.381086] [<ffffffff8103ff09>] mmput+0x5e/0xbb
> [ 12.381107] [<ffffffff81044d8c>] do_exit+0x39c/0x97e
> [ 12.381131] [<ffffffff810f49b4>] ? context_tracking_user_exit+0x79/0x116
> [ 12.381160] [<ffffffff8127f43a>] ? __this_cpu_preempt_check+0x13/0x15
> [ 12.381188] [<ffffffff810453f1>] do_group_exit+0x4c/0xc9
> [ 12.381212] [<ffffffff81045482>] SyS_exit_group+0x14/0x14
> [ 12.381238] [<ffffffff81524f52>] system_call_fastpath+0x12/0x17
> [ 12.381262] Code: 32 f5 ff 49 8b 45 78 48 8b 18 4c 8d 60 f0 48 83 eb 10 4d 8d 6c 24 10 4c 3b 6d b8 74 3d 49 8b 7c 24 08 83 bf 98 00 00 00 00 74 02 <0f> 0b f0 ff 8f 88 00 00 00 74 1d 4c 89 ef e8 61 96 15 00 4c 89
> [ 12.381445] RIP [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 12.381473] RSP <ffff8800bcaf3d28>
> [ 12.386659] ---[ end trace 5761ee18fca12427 ]---
> [ 12.386662] Fixing recursive fault but reboot is needed!
> [ 13.158240] e1000e 0000:00:19.0: irq 25 for MSI/MSI-X
> [ 13.259294] e1000e 0000:00:19.0: irq 25 for MSI/MSI-X
> [ 13.259468] IPv6: ADDRCONF(NETDEV_UP): lan0: link is not ready
> [ 16.790917] e1000e: lan0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
> [ 16.790957] IPv6: ADDRCONF(NETDEV_CHANGE): lan0: link becomes ready
> [ 18.846524] iwlwifi 0000:02:00.0: L1 Enabled - LTR Disabled
> [ 18.846742] iwlwifi 0000:02:00.0: Radio type=0x0-0x3-0x1
> [ 18.941594] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
> [ 19.145595] e1000e: lan0 NIC Link is Down
> [ 19.287399] e1000e 0000:00:19.0: irq 25 for MSI/MSI-X
> [ 19.391325] e1000e 0000:00:19.0: irq 25 for MSI/MSI-X
> [ 19.391475] IPv6: ADDRCONF(NETDEV_UP): lan0: link is not ready
> [ 19.573640] e1000e: lan0 NIC Link is Down
> [ 19.717813] e1000e 0000:00:19.0: irq 25 for MSI/MSI-X
> [ 19.819729] e1000e 0000:00:19.0: irq 25 for MSI/MSI-X
> [ 19.819883] IPv6: ADDRCONF(NETDEV_UP): lan0: link is not ready
> [ 22.938849] e1000e: lan0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
> [ 22.938889] IPv6: ADDRCONF(NETDEV_CHANGE): lan0: link becomes ready
> [ 23.404027] ------------[ cut here ]------------
> [ 23.404056] kernel BUG at mm/rmap.c:385!
> [ 23.404074] invalid opcode: 0000 [#2] PREEMPT SMP DEBUG_PAGEALLOC
> [ 23.404107] Modules linked in: i915 cfbfillrect cfbimgblt i2c_algo_bit fbcon bitblit softcursor cfbcopyarea font drm_kms_helper drm fb fbdev binfmt_misc fuse uvcvideo videobuf2_vmalloc videobuf2_memops arc4 videobuf2_core v4l2_common sdhci_pci iwldvm videodev media mac80211 i2c_i801 i2c_core sdhci mmc_core iwlwifi cfg80211 snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_pcm_oss snd_mixer_oss snd_pcm video backlight snd_timer snd
> [ 23.404353] CPU: 1 PID: 4506 Comm: synaptikscfg Tainted: G D 3.18.0-rc6-test-00001-gf5bc00c103ff #409
> [ 23.404395] Hardware name: Dell Inc. Latitude E6320/09PHH9, BIOS A08 10/18/2011
> [ 23.404425] task: ffff8800a337c2c0 ti: ffff88009f4ec000 task.ti: ffff88009f4ec000
> [ 23.404455] RIP: 0010:[<ffffffff81125f09>] [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 23.404494] RSP: 0018:ffff88009f4efd28 EFLAGS: 00010282
> [ 23.405766] RAX: ffff88009f54d010 RBX: ffff88009f54c488 RCX: 0000000000000000
> [ 23.407062] RDX: ffff88009f5a3a50 RSI: 0000000000000001 RDI: ffff88009f5a3a50
> [ 23.408352] RBP: ffff88009f4efd78 R08: 0000000000000000 R09: 0000000000000000
> [ 23.409597] R10: 0000000000000000 R11: ffff88009f54d020 R12: ffff88009f54d000
> [ 23.410816] R13: ffff88009f54d010 R14: ffff88009f5a3a50 R15: ffff88009f5a3a50
> [ 23.411998] FS: 0000000000000000(0000) GS:ffff88012d440000(0000) knlGS:0000000000000000
> [ 23.413167] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 23.414320] CR2: 00007f7a855608f0 CR3: 00000000a328c000 CR4: 00000000000407e0
> [ 23.415471] Stack:
> [ 23.416603] ffff8800a3390e00 ffff88009f54c498 ffff88009f54c498 ffff88009f54d000
> [ 23.417747] ffff88009f4efd78 ffff88009f54c420 ffff88009f4efdd8 0000000000000000
> [ 23.418892] 0000000000000000 ffff88009f54c420 ffff88009f4efdc8 ffffffff81119e26
> [ 23.420027] Call Trace:
> [ 23.421153] [<ffffffff81119e26>] free_pgtables+0x8e/0xcc
> [ 23.422273] [<ffffffff81121ac1>] exit_mmap+0x84/0x123
> [ 23.423411] [<ffffffff81044d48>] ? do_exit+0x358/0x97e
> [ 23.424537] [<ffffffff8103ff09>] mmput+0x5e/0xbb
> [ 23.425665] [<ffffffff81044d8c>] do_exit+0x39c/0x97e
> [ 23.426766] [<ffffffff810f49b4>] ? context_tracking_user_exit+0x79/0x116
> [ 23.427866] [<ffffffff8127f43a>] ? __this_cpu_preempt_check+0x13/0x15
> [ 23.428962] [<ffffffff810453f1>] do_group_exit+0x4c/0xc9
> [ 23.430064] [<ffffffff81045482>] SyS_exit_group+0x14/0x14
> [ 23.431162] [<ffffffff81524f52>] system_call_fastpath+0x12/0x17
> [ 23.432262] Code: 32 f5 ff 49 8b 45 78 48 8b 18 4c 8d 60 f0 48 83 eb 10 4d 8d 6c 24 10 4c 3b 6d b8 74 3d 49 8b 7c 24 08 83 bf 98 00 00 00 00 74 02 <0f> 0b f0 ff 8f 88 00 00 00 74 1d 4c 89 ef e8 61 96 15 00 4c 89
> [ 23.434722] RIP [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 23.435924] RSP <ffff88009f4efd28>
> [ 23.441996] ---[ end trace 5761ee18fca12428 ]---
> [ 23.442001] Fixing recursive fault but reboot is needed!
> [ 838.179454] ------------[ cut here ]------------
> [ 838.180658] kernel BUG at mm/rmap.c:385!
> [ 838.181843] invalid opcode: 0000 [#3] PREEMPT SMP DEBUG_PAGEALLOC
> [ 838.183046] Modules linked in: i915 cfbfillrect cfbimgblt i2c_algo_bit fbcon bitblit softcursor cfbcopyarea font drm_kms_helper drm fb fbdev binfmt_misc fuse uvcvideo videobuf2_vmalloc videobuf2_memops arc4 videobuf2_core v4l2_common sdhci_pci iwldvm videodev media mac80211 i2c_i801 i2c_core sdhci mmc_core iwlwifi cfg80211 snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_pcm_oss snd_mixer_oss snd_pcm video backlight snd_timer snd
> [ 838.186983] CPU: 1 PID: 6643 Comm: colord-sane Tainted: G D 3.18.0-rc6-test-00001-gf5bc00c103ff #409
> [ 838.188240] Hardware name: Dell Inc. Latitude E6320/09PHH9, BIOS A08 10/18/2011
> [ 838.189503] task: ffff8800c4fd8000 ti: ffff880079c6c000 task.ti: ffff880079c6c000
> [ 838.190765] RIP: 0010:[<ffffffff81125f09>] [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 838.192045] RSP: 0018:ffff880079c6fb68 EFLAGS: 00010286
> [ 838.193324] RAX: ffff8800c5a70150 RBX: ffff8800a6fd5748 RCX: 0000000000000000
> [ 838.194616] RDX: ffff8800a5379840 RSI: 0000000000000001 RDI: ffff8800a5379840
> [ 838.195879] RBP: ffff880079c6fbb8 R08: 0000000000000000 R09: 0000000000000000
> [ 838.197100] R10: 0000000000000000 R11: ffff8800c5a70160 R12: ffff8800c5a70140
> [ 838.198289] R13: ffff8800c5a70150 R14: ffff8800a5379840 R15: ffff8800a5379840
> [ 838.199448] FS: 0000000000000000(0000) GS:ffff88012d440000(0000) knlGS:0000000000000000
> [ 838.200604] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 838.201753] CR2: 00007fdfd692cde8 CR3: 0000000079d0d000 CR4: 00000000000407e0
> [ 838.202902] Stack:
> [ 838.204029] ffff88011e6fc540 ffff8800a6fd5758 ffff8800a6fd5758 ffff8800c5a70140
> [ 838.205180] ffff880079c6fbb8 ffff8800a6fd56e0 ffff880079c6fc18 0000000000000000
> [ 838.206328] 0000000000000000 ffff8800a6fd56e0 ffff880079c6fc08 ffffffff81119e26
> [ 838.207477] Call Trace:
> [ 838.208614] [<ffffffff81119e26>] free_pgtables+0x8e/0xcc
> [ 838.209762] [<ffffffff81121ac1>] exit_mmap+0x84/0x123
> [ 838.210897] [<ffffffff81044d48>] ? do_exit+0x358/0x97e
> [ 838.212020] [<ffffffff8103ff09>] mmput+0x5e/0xbb
> [ 838.213132] [<ffffffff81044d8c>] do_exit+0x39c/0x97e
> [ 838.214232] [<ffffffff8104ea16>] ? get_signal+0xdb/0x68a
> [ 838.215324] [<ffffffff8115de6d>] ? poll_select_copy_remaining+0xfe/0xfe
> [ 838.216420] [<ffffffff810453f1>] do_group_exit+0x4c/0xc9
> [ 838.217521] [<ffffffff8104ef82>] get_signal+0x647/0x68a
> [ 838.218612] [<ffffffff810f48bd>] ? context_tracking_user_enter+0xdb/0x159
> [ 838.219705] [<ffffffff8100228f>] do_signal+0x28/0x657
> [ 838.220796] [<ffffffff810c1e10>] ? __acct_update_integrals+0xbf/0xd4
> [ 838.221894] [<ffffffff81063e43>] ? preempt_count_sub+0xcd/0xdb
> [ 838.222998] [<ffffffff8106972e>] ? vtime_account_user+0x88/0x95
> [ 838.224105] [<ffffffff815243a3>] ? _raw_spin_unlock+0x32/0x47
> [ 838.225205] [<ffffffff810f49b4>] ? context_tracking_user_exit+0x79/0x116
> [ 838.226308] [<ffffffff810f49b4>] ? context_tracking_user_exit+0x79/0x116
> [ 838.227401] [<ffffffff810028fd>] do_notify_resume+0x3f/0x94
> [ 838.228495] [<ffffffff81525218>] int_signal+0x12/0x17
> [ 838.229581] Code: 32 f5 ff 49 8b 45 78 48 8b 18 4c 8d 60 f0 48 83 eb 10 4d 8d 6c 24 10 4c 3b 6d b8 74 3d 49 8b 7c 24 08 83 bf 98 00 00 00 00 74 02 <0f> 0b f0 ff 8f 88 00 00 00 74 1d 4c 89 ef e8 61 96 15 00 4c 89
> [ 838.231909] RIP [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 838.233003] RSP <ffff880079c6fb68>
> [ 838.234248] ---[ end trace 5761ee18fca12429 ]---
> [ 838.234251] Fixing recursive fault but reboot is needed!
> [ 1806.784267] ------------[ cut here ]------------
> [ 1806.785322] kernel BUG at mm/rmap.c:385!
> [ 1806.786361] invalid opcode: 0000 [#4] PREEMPT SMP DEBUG_PAGEALLOC
> [ 1806.787397] Modules linked in: i915 cfbfillrect cfbimgblt i2c_algo_bit fbcon bitblit softcursor cfbcopyarea font drm_kms_helper drm fb fbdev binfmt_misc fuse uvcvideo videobuf2_vmalloc videobuf2_memops arc4 videobuf2_core v4l2_common sdhci_pci iwldvm videodev media mac80211 i2c_i801 i2c_core sdhci mmc_core iwlwifi cfg80211 snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_pcm_oss snd_mixer_oss snd_pcm video backlight snd_timer snd
> [ 1806.790682] CPU: 1 PID: 8135 Comm: DNS Resolver #7 Tainted: G D 3.18.0-rc6-test-00001-gf5bc00c103ff #409
> [ 1806.791728] Hardware name: Dell Inc. Latitude E6320/09PHH9, BIOS A08 10/18/2011
> [ 1806.792779] task: ffff8800b3d40000 ti: ffff880079e34000 task.ti: ffff880079e34000
> [ 1806.793816] RIP: 0010:[<ffffffff81125f09>] [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 1806.794863] RSP: 0018:ffff880079e37d38 EFLAGS: 00010282
> [ 1806.795894] RAX: ffff8800b508d790 RBX: ffff8800bcaa4e28 RCX: 0000000000000000
> [ 1806.796948] RDX: ffff880124ce0f20 RSI: 0000000000000001 RDI: ffff880124ce0f20
> [ 1806.798011] RBP: ffff880079e37d88 R08: 0000000000000000 R09: 0000000000000000
> [ 1806.799048] R10: 00007fc2827f9db0 R11: ffff8800b508d7a0 R12: ffff8800b508d780
> [ 1806.800105] R13: ffff8800b508d790 R14: ffff880124ce0f20 R15: ffff880124ce0f20
> [ 1806.801143] FS: 00007fc2827fa700(0000) GS:ffff88012d440000(0000) knlGS:0000000000000000
> [ 1806.802206] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1806.803244] CR2: 00007fc2c6b87000 CR3: 00000000a3063000 CR4: 00000000000407e0
> [ 1806.804305] Stack:
> [ 1806.805329] 00007fc280754000 ffff8800bcaa4e38 ffff8800bcaa4e38 ffff8800b508d780
> [ 1806.806382] 0000000081098bfb ffff8800bcaa4dc0 ffff880079e37df8 00007fc27ff00000
> [ 1806.807467] 00007fc280a00000 ffff8800bcaa4dc0 ffff880079e37dd8 ffffffff81119e26
> [ 1806.808536] Call Trace:
> [ 1806.809570] [<ffffffff81119e26>] free_pgtables+0x8e/0xcc
> [ 1806.810617] [<ffffffff8111fe4c>] unmap_region+0xc8/0xec
> [ 1806.811658] [<ffffffff81270329>] ? __rb_erase_color+0x122/0x1f9
> [ 1806.812724] [<ffffffff8112192b>] do_munmap+0x275/0x2f7
> [ 1806.813792] [<ffffffff811219f5>] vm_munmap+0x48/0x61
> [ 1806.814841] [<ffffffff81121a34>] SyS_munmap+0x26/0x2f
> [ 1806.815884] [<ffffffff81524f52>] system_call_fastpath+0x12/0x17
> [ 1806.816951] Code: 32 f5 ff 49 8b 45 78 48 8b 18 4c 8d 60 f0 48 83 eb 10 4d 8d 6c 24 10 4c 3b 6d b8 74 3d 49 8b 7c 24 08 83 bf 98 00 00 00 00 74 02 <0f> 0b f0 ff 8f 88 00 00 00 74 1d 4c 89 ef e8 61 96 15 00 4c 89
> [ 1806.819300] RIP [<ffffffff81125f09>] unlink_anon_vmas+0x12b/0x169
> [ 1806.820457] RSP <ffff880079e37d38>
> [ 1806.822068] ---[ end trace 5761ee18fca1242a ]---
> --
> Michal Hocko
> SUSE Labs

Attachment: mm-prevent-endless-growth-of-anon_vma-hierarchy-v2
Description: Binary data

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