From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1523341373; cv=none; d=google.com; s=arc-20160816; b=p+TnSr8/PwWSAnI2rxgYGN99fv0EadUp1qRQW1Z30M0GliAl5s3hritKz9f4nH0HzX 4HKwBkhZoOvWce7EVnN46sBHEt4iDsnCrtuH1Dxn40yFBIsJyY2Ws2oY1K0WnBuGRTAQ fSbNMnNvaDipkELFjTW2o4d932CGyoRNTj46F0vGpwiws4dI5FtYCdEx4RjZoRJngXBV YUce9mLkeHHsJCNCeaotD/u+NtBv8CexHknkmwt20MPwkqIvny8f8FOzoEqB0Y4ZqOJv RVYgkXSmr/xeVca9eDm35wSSmM3ULSevkrNSrvtCB0bj25IcFS1/kq+5LDEo4aJ9PHpK TnyA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:sender:dkim-signature :arc-authentication-results; bh=3Cl0YF2X+s0cWOAAkVhffMS1OsSTiBzr00CyDM6z7A0=; b=M6cLZ3l3fnrYKy137IJn8JrBHQFGUoNdpvqhctNMlgJUnSZ0B+2PXFGaGDPzpJ94Yx 0+hw8itvWVi3hSVGY8XXNgGrDIiV7aNFd5EjCAvNKqQj9SHhy0SL1Mp5R36zsavqm/As IpB4VsPiUMLv+4Z/RUuVRad+F6OWTvN8wLQdKt6stAsHrV8z6JHY98E0bD2x3xYUS+xx P0no01V4LsmLOmitRJZ+w22Tv+nImbasJBJMTWz+c993rNKPq5v03Fo/k9f/VFvIwW8X 4DeOxEn60oll0webHGf4206BHo+V342Kzrr8jO6VTLFqhiKCox01ZIoVEF/BZYMLmSiK Rc9A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=sUM+kMjo; spf=pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=sUM+kMjo; spf=pass (google.com: domain of minchan.kim@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com X-Google-Smtp-Source: AIpwx49LUtSPgBxLuKSEocDH5O1Nf7SvKL2u9qwAsLV61QM7lwoU2hayfz8bfyw/sBJ9JgSm5AW7Ag== Sender: Minchan Kim Date: Tue, 10 Apr 2018 15:22:48 +0900 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , LKML , Greg KH Subject: Re: [PATCH v3 4/4] zram: introduce zram memory tracking Message-ID: <20180410062248.GC38000@rodete-desktop-imager.corp.google.com> References: <20180409055435.135695-1-minchan@kernel.org> <20180409055435.135695-5-minchan@kernel.org> <20180410000305.GA6942@jagdpanzerIV> <20180410004109.GA1580@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180410004109.GA1580@jagdpanzerIV> User-Agent: Mutt/1.9.2 (2017-12-15) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597246846962715384?= X-GMAIL-MSGID: =?utf-8?q?1597339203717180628?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: I will fix and resend tomorrow. Huge thanks, Sergey! On Tue, Apr 10, 2018 at 09:41:09AM +0900, Sergey Senozhatsky wrote: > I think zram_debugfs_unregister() is called both from zram_remove() and > from destroy_devices(), which explodes: > > [ 1906.467981] BUG: unable to handle kernel NULL pointer dereference at 00000000000000b8 > [ 1906.468007] PGD 80000003d5050067 P4D 80000003d5050067 PUD 3fa97d067 PMD 0 > [ 1906.468029] Oops: 0002 [#1] PREEMPT SMP PTI > [ 1906.468035] Modules linked in: zram(-) zsmalloc mousedev hid_generic rndis_host usbhid cdc_ether usbnet hid snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core coretemp snd_pcm hwmon snd_timer snd r8169 i2c_i801 soundcore mii xhci_pci xhci_hcd usbcore sd_mod usb_common > [ 1906.468069] RIP: 0010:down_write+0x29/0x46 > [ 1906.468073] RSP: 0018:ffffb9dd0480fdd0 EFLAGS: 00010246 > [ 1906.468077] RAX: 00000000000000b8 RBX: 00000000000000b8 RCX: 0000000000000001 > [ 1906.468082] RDX: ffffffff00000001 RSI: 0000000000000045 RDI: ffffffffb1baa40a > [ 1906.468086] RBP: ffffa189fce9fbd8 R08: ffffb9dd0480fddc R09: 0000000000000007 > [ 1906.468091] R10: ffffb9dd0480fe40 R11: 0000000000000000 R12: ffffa189fce9fbd8 > [ 1906.468095] R13: ffffffffb23cab54 R14: 0000000000000000 R15: 0000000000000000 > [ 1906.468100] FS: 00007fbc72cd2b80(0000) GS:ffffa18a1ed00000(0000) knlGS:0000000000000000 > [ 1906.468105] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1906.468110] CR2: 00000000000000b8 CR3: 00000003b4570003 CR4: 00000000001606e0 > [ 1906.468114] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 1906.468119] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 1906.468123] Call Trace: > [ 1906.468130] debugfs_remove_recursive+0x40/0x15e > [ 1906.468136] zram_remove+0x7f/0xf6 [zram] > [ 1906.468141] ? hot_remove_store+0x93/0x93 [zram] > [ 1906.468146] zram_remove_cb+0xd/0x10 [zram] > [ 1906.468150] idr_for_each+0x50/0xc7 > [ 1906.468155] destroy_devices+0x32/0x5c [zram] > [ 1906.468160] SyS_delete_module+0xfd/0x19a > [ 1906.468165] do_syscall_64+0x17e/0x195 > [ 1906.468169] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > [ 1906.468174] RIP: 0033:0x7fbc723cb5d7 > [ 1906.468177] RSP: 002b:00007ffc40316d48 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 > [ 1906.468182] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbc723cb5d7 > [ 1906.468187] RDX: 000000000000000a RSI: 0000000000000800 RDI: 00000000013e7778 > [ 1906.468191] RBP: 00000000013e7710 R08: 00007ffc40315cc1 R09: 0000000000000000 > [ 1906.468196] R10: 00000000000008b2 R11: 0000000000000206 R12: 00007ffc403188b4 > [ 1906.468201] R13: 0000000000000000 R14: 00000000013e7710 R15: 00000000013e7260 > [ 1906.468761] Code: ff ff 0f 1f 44 00 00 53 31 d2 48 89 fb be 45 00 00 00 48 c7 c7 0a a4 ba b1 e8 ef bf b9 ff 48 89 d8 48 ba 01 00 00 00 ff ff ff ff 48 0f c1 10 85 d2 74 05 e8 9e bd ff ff 65 48 8b 04 25 80 4d > [ 1906.469296] RIP: down_write+0x29/0x46 RSP: ffffb9dd0480fdd0 > [ 1906.469995] CR2: 00000000000000b8 > [ 1906.475689] ---[ end trace 10d42324537dfb4c ]--- > > -ss