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McKenney" , Matthew Wilcox , Laurent Dufour , David Rientjes , Axel Rasmussen , Suren Baghdasaryan , Vlastimil Babka , Rik van Riel , Peter Zijlstra , Michel Lespinasse , Jerome Glisse , Minchan Kim , Joel Fernandes , Rom Lemarchand , Liam Howlett Subject: [PATCH v4 44/66] ipc/shm: Use VMA iterator instead of linked list Thread-Topic: [PATCH v4 44/66] ipc/shm: Use VMA iterator instead of linked list Thread-Index: AQHX5r/y/5/uIeddpE6IuVIz7n6Hew== Date: Wed, 1 Dec 2021 14:30:10 +0000 Message-ID: <20211201142918.921493-45-Liam.Howlett@oracle.com> References: <20211201142918.921493-1-Liam.Howlett@oracle.com> In-Reply-To: <20211201142918.921493-1-Liam.Howlett@oracle.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: git-send-email 2.30.2 x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 17935539-46e1-407d-0de7-08d9b4d72566 x-ms-traffictypediagnostic: SA2PR10MB4508: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:7219; 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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SN6PR10MB3022.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 17935539-46e1-407d-0de7-08d9b4d72566 X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Dec 2021 14:30:10.6549 (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: vHO0KC0PlWHXHtIjDgP80fU/8zuAcuVdnIGvQGS7tiuwqZQhHiSg9TyfKg4TXyGgfS+d5MNglzNwt4POKxddPg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA2PR10MB4508 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10184 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 spamscore=0 adultscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112010081 X-Proofpoint-ORIG-GUID: OMytN7aHT-f1xiWP2Pjh4iFqkHAwrZmr X-Proofpoint-GUID: OMytN7aHT-f1xiWP2Pjh4iFqkHAwrZmr Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Liam R. Howlett" The VMA iterator is faster than the linked llist, and it can be walked even when VMAs are being removed from the address space, so there's no need to keep track of 'next'. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Liam R. Howlett --- ipc/shm.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/ipc/shm.c b/ipc/shm.c index b3048ebd5c31..7d86f058fb86 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1721,7 +1721,7 @@ long ksys_shmdt(char __user *shmaddr) #ifdef CONFIG_MMU loff_t size =3D 0; struct file *file; - struct vm_area_struct *next; + VMA_ITERATOR(vmi, mm, addr); #endif =20 if (addr & ~PAGE_MASK) @@ -1751,12 +1751,9 @@ long ksys_shmdt(char __user *shmaddr) * match the usual checks anyway. So assume all vma's are * above the starting address given. */ - vma =3D find_vma(mm, addr); =20 #ifdef CONFIG_MMU - while (vma) { - next =3D vma->vm_next; - + for_each_vma(vmi, vma) { /* * Check if the starting address would match, i.e. it's * a fragment created by mprotect() and/or munmap(), or it @@ -1774,6 +1771,7 @@ long ksys_shmdt(char __user *shmaddr) file =3D vma->vm_file; size =3D i_size_read(file_inode(vma->vm_file)); do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL); + mas_pause(&vmi.mas); /* * We discovered the size of the shm segment, so * break out of here and fall through to the next @@ -1781,10 +1779,9 @@ long ksys_shmdt(char __user *shmaddr) * searching for matching vma's. */ retval =3D 0; - vma =3D next; + vma =3D vma_next(&vmi); break; } - vma =3D next; } =20 /* @@ -1794,17 +1791,19 @@ long ksys_shmdt(char __user *shmaddr) */ size =3D PAGE_ALIGN(size); while (vma && (loff_t)(vma->vm_end - addr) <=3D size) { - next =3D vma->vm_next; - /* finding a matching vma now does not alter retval */ if ((vma->vm_ops =3D=3D &shm_vm_ops) && ((vma->vm_start - addr)/PAGE_SIZE =3D=3D vma->vm_pgoff) && - (vma->vm_file =3D=3D file)) + (vma->vm_file =3D=3D file)) { do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL); - vma =3D next; + mas_pause(&vmi.mas); + } + + vma =3D vma_next(&vmi); } =20 #else /* CONFIG_MMU */ + vma =3D vma_lookup(mm, addr); /* under NOMMU conditions, the exact address to be destroyed must be * given */ --=20 2.30.2