From:   Mike Christie <michael.christie@oracle.com>
To:     hch@infradead.org, stefanha@redhat.com, jasowang@redhat.com,
        mst@redhat.com, sgarzare@redhat.com,
        virtualization@lists.linux-foundation.org, brauner@kernel.org,
        ebiederm@xmission.com, torvalds@linux-foundation.org,
        konrad.wilk@oracle.com, linux-kernel@vger.kernel.org
Cc:     Mike Christie <michael.christie@oracle.com>
Subject: [PATCH 05/11] fork/vm: Move common PF_IO_WORKER behavior to new flag
Date:   Fri, 10 Mar 2023 16:03:26 -0600
Message-Id: <20230310220332.5309-6-michael.christie@oracle.com>
In-Reply-To: <20230310220332.5309-1-michael.christie@oracle.com>
References: <20230310220332.5309-1-michael.christie@oracle.com>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?plYnWi5S/0bhldyuo51xnXyGBrORCNZXLFbMtbIq6NyEEgiJBzOZw0FHT0Q+?=
 =?us-ascii?Q?1OtgbE6fkRLIHYI9APLR0NaQ6Jo4HLzLedQyk4y+4a0cet7nGaWt1jCeFAWx?=
 =?us-ascii?Q?EN22AN+pxvI5UY+TeXTYfADVTzCSAGxQglerIe/n2IRTPNdfW2HROYYqGDPN?=
 =?us-ascii?Q?FywQIHsVcW+W785vsPy5ypSSTZzDN6E5Ragq11GBbNIFywv/xo5Y+ui5rH1/?=
 =?us-ascii?Q?HW250+VOuLNsv4/V+ZeVN/wLoZq14Z7sLHuwQbZliHcrMgm0CpjNZQ6SRYHd?=
 =?us-ascii?Q?LltSF0MpNV0vLMIcmWJBCAFbtdZF6J1WIvcMQl36+oYSj8NhHCgSKztv1l94?=
 =?us-ascii?Q?zrnC68hE0LYFMQ7LGv8GqVU2FUPjs7Gp227Z5TN5C8E8aeMkuVe8s8uJAId4?=
 =?us-ascii?Q?Nmcu92khF6S9DmUGR7u2h2C8FTg2+YypQPHhcSYtSxmfpH7rF6wI1D+f+H9/?=
 =?us-ascii?Q?Y3izo0/CCS821ROF7G74aHeoVkcwRltoiLGMZOkToLQ9lqcae/pO3gwAc3UH?=
 =?us-ascii?Q?3yC7ItDCht3A1WiIdkWCpObEXVl/dSKaCo2EtAHwv78HnFeWzEui6JA+2AMm?=
 =?us-ascii?Q?KElORpbPyyMgVMWI3SQ90EHSag+UxtJGIWo9JyRC+u/OznMxoamuDtf3yCLj?=
 =?us-ascii?Q?rChtdyr8jVvjk/4P8uICGABSOss8OgeWLXbyYTPmJtXkWBQWtVsO/sJAK7Cp?=
 =?us-ascii?Q?hIOmHgVBebHirj3d1eMVH3AShacVfYzg4+rCd4ZZbH5OYdXFg7e7W1RDizNj?=
 =?us-ascii?Q?hUgK06Vt9eC52A8sN2ENCkIG8QxiNH14WaSwh8zeztdiH7YxEmPKGAPBAjWH?=
 =?us-ascii?Q?3mK72kmGz0xuKm+3yy7xRDj3RNLIvQWunEZmkHuPbb2Ujo4BDAVZ5O8/34G6?=
 =?us-ascii?Q?gbscZenO/7GzQtmWTDADcJtxEs1Y2OT4Yo7vl0Xqta65MG30mcTPDY5UCUke?=
 =?us-ascii?Q?35g4hK2zwiCvRPDVkT6zvJTLRBN0HH9/Zt03uJx2iCIzed04e4FJO63hvG5n?=
 =?us-ascii?Q?rTXVdGa+mbCDjEEfBaaeMbBkcxCT3rn8EgAQoJFO5hp4mLzfNPi2EmJzP769?=
 =?us-ascii?Q?xP9WP+NYVPK/glU+rqSLwS6CLjxtyHKWA4FAcKer2aiZaTIuveMcKFZMfMBW?=
 =?us-ascii?Q?I3KR7YXqWO0OCKzPgMIBkIsv9ONM3ZmONZABX7AUf+rxJ4FzuKlVW2y+gQ2a?=
 =?us-ascii?Q?MHuKaJLAulhwwPtNWF6mKbwAUJDcZGHgcuwQ+orz2sJ3Bk1IldfBi316M6Rm?=
 =?us-ascii?Q?2UduKM+N7H5F8A7KIL+V8sYg3d4URcJYxVojH9sGhtTbP967UfVnn3zxLV6k?=
 =?us-ascii?Q?r6uF4RTHSf0Y7ehrTv/eqIgD8SMaYaCL1L/DIDW3FD5/x7KSezEp/TTaB33s?=
 =?us-ascii?Q?lm+2aJmuF/BH4tGWa3oq8rYnzugCffs20OnrHhIUlSpw1CptazaLcL3Yy9tW?=
 =?us-ascii?Q?QIvHUGTNW02VIBeJjSfq6K4yEM4PqRXSUWx8FsqEmEg4wyVxdmxN/CV3am1d?=
 =?us-ascii?Q?WJT6QXw18UkpX28wFSaggHQ0NWCerMNS5MV0h+3WooaWC6uTOKmaTGNHQC1z?=
 =?us-ascii?Q?fxVasZD6zTM0cw9//6qTiiHHG4RC09pRB0qfa5vqUTbmoK5iX/uNegRDCrFj?=
 =?us-ascii?Q?Cg=3D=3D?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?us-ascii?Q?zXXTJAHQYJN1Suy++dGMQR2VQP6TusHeEgMoro7FABPGL7S6xfJGvTyaCBE8?=
 =?us-ascii?Q?irmxMCjrvyKdLI+fH1+wE2+vP0azY65NrogUTJus9F2/estT2cNrsQn7wGLI?=
 =?us-ascii?Q?TyHfX6fUclyn/VSCYbF/w/HjutC704RXFFoeEYj8OA6dC8ht8np1/FGOG26d?=
 =?us-ascii?Q?G2g2M9rYdXN/Uipwdpx01wV9ELGHO7xcYt086TXt3mKCWtToI26Dx08P3g8L?=
 =?us-ascii?Q?hsD5tLQJpDuWBiMzKldOQkfM1AFDhcdVDLH/0w2JoJN1DbFiyOjb3If+vNOY?=
 =?us-ascii?Q?7nLRYcSLQVpX/GwqKyUfaLqmvEMfRSf6IiP0EKNW2xX4SZTM+yNSuDVoXGx8?=
 =?us-ascii?Q?aqM2QhMnDnnKS2ka9PwsTfEUaCSbInGKT6fyW8gqDHBqrOOBMGCMESiP1cuy?=
 =?us-ascii?Q?BF77PReoUePoTdWBFwftxccfpWSBjK0ok49Xm5gTJlh0cbuQZnv8W2WFxEl0?=
 =?us-ascii?Q?c6IGd+EmenHi8HIJNiq1Evt0QW6GtFo1mghsb2FMfcKsKiYUyWrqRZ8PVcy4?=
 =?us-ascii?Q?WHEXZyLppn8m8N14M0jKf1Hkpjxqeh1bQHWntmIU3rrWWjs7sJTNL2VO4W3Z?=
 =?us-ascii?Q?V552COc3GI11SQDPJf/oHs4faTiT12Z+H4DDZC9zqndCoHomRvy3lwZb+8PH?=
 =?us-ascii?Q?lNrpnz8MBq7pnqMDJlpz2LfjpP701Hea5Uc8exRi0OYRnBuhYLn1LU3XMbY8?=
 =?us-ascii?Q?gclqFkYl8RkyrRRNY8HH/SjJYDEMN4FQn4rxi2SoC3IbzFf4Ewg1vN5MnCj0?=
 =?us-ascii?Q?jkAF5HdMu77bHugR7aLPBPYXLKFO+l43CbnLlgXxmId72Oqpcxtwshn/tDgj?=
 =?us-ascii?Q?ylJ+h8cwANdkiplpwz+aUXO85gymEKdeewXURttKQ2oSxKpA6ZfEh323kt/A?=
 =?us-ascii?Q?Wlv/K2QuwpryOLHt8ihNG4btzGY+9jeJ3lnQowzXhjaSvYwNmyQPSllpIMQi?=
 =?us-ascii?Q?qMrzgMakMJSw71WMfvNVhcDYkHrbd/t0ybbHSAtm+ylCLk2wDsQXgS24doyW?=
 =?us-ascii?Q?t8XZzQFMSNtAKZ5FdaWfUcUEfw=3D=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 37dd8d1d-acb5-4aec-487c-08db21b35024
X-MS-Exchange-CrossTenant-AuthSource: DM5PR10MB1466.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Mar 2023 22:03:43.1881
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: ownaPa07fGzhBSPeOCR/8rGzS0p1R/fIECbguWTIRoZPM93lHvickUDZpY8G7o2HyGMC/nrmBzJQbiilJGlhIW09WQNO4u31JskvKHnNuhk=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR10MB6514
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22
 definitions=2023-03-10_10,2023-03-10_01,2023-02-09_01
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 adultscore=0
 phishscore=0 suspectscore=0 malwarescore=0 spamscore=0 bulkscore=0
 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2212070000 definitions=main-2303100176
X-Proofpoint-GUID: -m8s1-iiWfoHuUKKL3ibB7FqOMVbnxur
X-Proofpoint-ORIG-GUID: -m8s1-iiWfoHuUKKL3ibB7FqOMVbnxur
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

This adds a new flag, PF_USER_WORKER, that's used for behavior common to
to both PF_IO_WORKER and users like vhost which will use a new helper
instead of create_io_thread because they require different behavior for
operations like signal handling.

The common behavior PF_USER_WORKER covers is the vm reclaim handling.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/linux/sched.h      | 2 +-
 include/linux/sched/task.h | 1 +
 kernel/fork.c              | 3 +++
 mm/vmscan.c                | 4 ++--
 4 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 853d08f7562b..2ca9269332c1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1723,7 +1723,7 @@ extern struct pid *cad_pid;
 #define PF_MEMALLOC		0x00000800	/* Allocating memory */
 #define PF_NPROC_EXCEEDED	0x00001000	/* set_user() noticed that RLIMIT_NPROC was exceeded */
 #define PF_USED_MATH		0x00002000	/* If unset the fpu must be initialized before use */
-#define PF__HOLE__00004000	0x00004000
+#define PF_USER_WORKER		0x00004000	/* Kernel thread cloned from userspace thread */
 #define PF_NOFREEZE		0x00008000	/* This thread should not be frozen */
 #define PF__HOLE__00010000	0x00010000
 #define PF_KSWAPD		0x00020000	/* I am kswapd */
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 268c77a42155..2950e83d5382 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -27,6 +27,7 @@ struct kernel_clone_args {
 	int exit_signal;
 	u32 kthread:1;
 	u32 io_thread:1;
+	u32 user_worker:1;
 	unsigned long stack;
 	unsigned long stack_size;
 	unsigned long tls;
diff --git a/kernel/fork.c b/kernel/fork.c
index cb8f85c88c75..0dec38276363 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2100,6 +2100,8 @@ static __latent_entropy struct task_struct *copy_process(
 	p->flags &= ~PF_KTHREAD;
 	if (args->kthread)
 		p->flags |= PF_KTHREAD;
+	if (args->user_worker)
+		p->flags |= PF_USER_WORKER;
 	if (args->io_thread) {
 		/*
 		 * Mark us an IO worker, and block any signal that isn't
@@ -2627,6 +2629,7 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
 		.fn		= fn,
 		.fn_arg		= arg,
 		.io_thread	= 1,
+		.user_worker	= 1,
 	};
 
 	return copy_process(NULL, 0, node, &args);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index bf3eedf0209c..86c27b08041e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1141,12 +1141,12 @@ void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)
 	DEFINE_WAIT(wait);
 
 	/*
-	 * Do not throttle IO workers, kthreads other than kswapd or
+	 * Do not throttle user workers, kthreads other than kswapd or
 	 * workqueues. They may be required for reclaim to make
 	 * forward progress (e.g. journalling workqueues or kthreads).
 	 */
 	if (!current_is_kswapd() &&
-	    current->flags & (PF_IO_WORKER|PF_KTHREAD)) {
+	    current->flags & (PF_USER_WORKER|PF_KTHREAD)) {
 		cond_resched();
 		return;
 	}
-- 
2.25.1