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Tue, 30 Jun 2020 06:12:52 +0000 From: Song Liu To: Alexei Starovoitov CC: bpf , Network Development , LKML , Peter Zijlstra , Alexei Starovoitov , Daniel Borkmann , Kernel Team , John Fastabend , KP Singh , Andrii Nakryiko Subject: Re: [PATCH v4 bpf-next 2/4] bpf: introduce helper bpf_get_task_stack() Thread-Topic: [PATCH v4 bpf-next 2/4] bpf: introduce helper bpf_get_task_stack() Thread-Index: AQHWTdpOOeBrZxmplkiL+hzLkKWLhajwj1OAgAAf8QA= Date: Tue, 30 Jun 2020 06:12:52 +0000 Message-ID: <9FF7383E-2D6B-4B6C-B996-50347E0A2F94@fb.com> References: <20200629055530.3244342-1-songliubraving@fb.com> <20200629055530.3244342-3-songliubraving@fb.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.80.23.2.2) authentication-results: gmail.com; dkim=none (message not signed) header.d=none;gmail.com; dmarc=none action=none header.from=fb.com; x-originating-ip: [2620:10d:c091:480::1:4392] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 0d34432f-d6aa-4622-bfd8-08d81cbc9f92 x-ms-traffictypediagnostic: BYAPR15MB2647: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-fb-source: Internal x-ms-oob-tlc-oobclassifiers: OLM:6430; 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charset="us-ascii" Content-ID: <4959B192D5F99C47B5A07ECE53AC44B8@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB2999.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0d34432f-d6aa-4622-bfd8-08d81cbc9f92 X-MS-Exchange-CrossTenant-originalarrivaltime: 30 Jun 2020 06:12:52.7830 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: o/o73N+pminW8SdR+7GmsDfHrcVyq2sr4/r+bjLbk9+lxkr6bDQnQW41QfqZblRkq9yiRRjS7ndgeYTGF8HYwA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2647 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-06-30_01:2020-06-30,2020-06-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxlogscore=999 adultscore=0 lowpriorityscore=0 mlxscore=0 malwarescore=0 bulkscore=0 phishscore=0 spamscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 cotscore=-2147483648 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006300047 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > On Jun 29, 2020, at 9:18 PM, Alexei Starovoitov wrote: >=20 > On Sun, Jun 28, 2020 at 10:58 PM Song Liu wrote: >>=20 >> Introduce helper bpf_get_task_stack(), which dumps stack trace of given >> task. This is different to bpf_get_stack(), which gets stack track of >> current task. One potential use case of bpf_get_task_stack() is to call >> it from bpf_iter__task and dump all /proc//stack to a seq_file. >>=20 >> bpf_get_task_stack() uses stack_trace_save_tsk() instead of >> get_perf_callchain() for kernel stack. The benefit of this choice is tha= t >> stack_trace_save_tsk() doesn't require changes in arch/. The downside of >> using stack_trace_save_tsk() is that stack_trace_save_tsk() dumps the >> stack trace to unsigned long array. For 32-bit systems, we need to >> translate it to u64 array. >>=20 >> Acked-by: Andrii Nakryiko >> Signed-off-by: Song Liu >=20 > It doesn't apply: > Applying: bpf: Introduce helper bpf_get_task_stack() > Using index info to reconstruct a base tree... > error: patch failed: kernel/bpf/stackmap.c:471 > error: kernel/bpf/stackmap.c: patch does not apply > error: Did you hand edit your patch? > It does not apply to blobs recorded in its index. > Patch failed at 0002 bpf: Introduce helper bpf_get_task_stack() Hmm.. seems "git format-patch -b" (--ignore-space-change) breaks it: # without -b, works fine $ git format-patch HEAD~1 0001-bpf-introduce-helper-bpf_get_task_stack.patch $ git reset --hard HEAD~1 HEAD is now at c385fe4fbd7bc perf: expose get/put_callchain_entry() $ git am ./0001-bpf-introduce-helper-bpf_get_task_stack.patch Applying: bpf: introduce helper bpf_get_task_stack() # with -b, doesn't apply :( $ git format-patch -b HEAD~1 0001-bpf-introduce-helper-bpf_get_task_stack.patch $ git reset --hard HEAD~1 HEAD is now at c385fe4fbd7bc perf: expose get/put_callchain_entry() $ git am ./0001-bpf-introduce-helper-bpf_get_task_stack.patch Applying: bpf: introduce helper bpf_get_task_stack() error: patch failed: kernel/bpf/stackmap.c:471 error: kernel/bpf/stackmap.c: patch does not apply Patch failed at 0001 bpf: introduce helper bpf_get_task_stack() hint: Use 'git am --show-current-patch' to see the failed patch When you have resolved this problem, run "git am --continue". If you prefer to skip this patch, run "git am --skip" instead. To restore the original branch and stop patching, run "git am --abort". Let me see how to fix it...