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Fri, 21 Aug 2020 08:01:41 -0700 Received: by devvm1096.prn0.facebook.com (Postfix, from userid 111017) id 25EDB3441047; Fri, 21 Aug 2020 08:01:35 -0700 (PDT) Smtp-Origin-Hostprefix: devvm From: Roman Gushchin Smtp-Origin-Hostname: devvm1096.prn0.facebook.com To: CC: , Alexei Starovoitov , Daniel Borkmann , , , Johannes Weiner , Shakeel Butt , , Roman Gushchin Smtp-Origin-Cluster: prn0c01 Subject: [PATCH bpf-next v4 01/30] mm: support nesting memalloc_use_memcg() Date: Fri, 21 Aug 2020 08:01:05 -0700 Message-ID: <20200821150134.2581465-2-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200821150134.2581465-1-guro@fb.com> References: <20200821150134.2581465-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-21_08:2020-08-21,2020-08-21 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 clxscore=1015 spamscore=0 impostorscore=0 mlxscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 lowpriorityscore=0 suspectscore=1 phishscore=0 bulkscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008210141 X-FB-Internal: deliver X-Rspamd-Queue-Id: C80791800BCF0 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Johannes Weiner Support nesting of memalloc_use_memcg() to be able to use from an interrupt context. Make memalloc_use_memcg() return the old memcg and convert existing users to a stacking model. Delete the unused memalloc_unuse_memcg(). Roman: I've rephrased the original commit log, because it was focused on the accounting problem related to loop devices. I made it less specific, so it can work for bpf too. Also rebased to the current state of the mm tree. The original patch can be found here: https://lkml.org/lkml/2020/5/28/806 Signed-off-by: Johannes Weiner Signed-off-by: Roman Gushchin Reviewed-by: Shakeel Butt --- fs/buffer.c | 6 +++--- fs/notify/fanotify/fanotify.c | 5 +++-- fs/notify/inotify/inotify_fsnotify.c | 5 +++-- include/linux/sched/mm.h | 28 +++++++++------------------- mm/memcontrol.c | 6 +++--- 5 files changed, 21 insertions(+), 29 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 061dd202979d..97ef480db0da 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -842,13 +842,13 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, struct buffer_head *bh, *head; gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT; long offset; - struct mem_cgroup *memcg; + struct mem_cgroup *memcg, *old_memcg; if (retry) gfp |= __GFP_NOFAIL; memcg = get_mem_cgroup_from_page(page); - memalloc_use_memcg(memcg); + old_memcg = memalloc_use_memcg(memcg); head = NULL; offset = PAGE_SIZE; @@ -867,7 +867,7 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, set_bh_page(bh, page, offset); } out: - memalloc_unuse_memcg(); + memalloc_use_memcg(old_memcg); mem_cgroup_put(memcg); return head; /* diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index c942910a8649..0e59fa57f6d7 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -531,6 +531,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir); const struct path *path = fsnotify_data_path(data, data_type); unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + struct mem_cgroup *old_memcg; struct inode *child = NULL; bool name_event = false; @@ -580,7 +581,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, gfp |= __GFP_RETRY_MAYFAIL; /* Whoever is interested in the event, pays for the allocation. */ - memalloc_use_memcg(group->memcg); + old_memcg = memalloc_use_memcg(group->memcg); if (fanotify_is_perm_event(mask)) { event = fanotify_alloc_perm_event(path, gfp); @@ -608,7 +609,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, event->pid = get_pid(task_tgid(current)); out: - memalloc_unuse_memcg(); + memalloc_use_memcg(old_memcg); return event; } diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c index a65cf8c9f600..8017a51561c4 100644 --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -66,6 +66,7 @@ static int inotify_one_event(struct fsnotify_group *group, u32 mask, int ret; int len = 0; int alloc_len = sizeof(struct inotify_event_info); + struct mem_cgroup *old_memcg; if ((inode_mark->mask & FS_EXCL_UNLINK) && path && d_unlinked(path->dentry)) @@ -87,9 +88,9 @@ static int inotify_one_event(struct fsnotify_group *group, u32 mask, * trigger OOM killer in the target monitoring memcg as it may have * security repercussion. */ - memalloc_use_memcg(group->memcg); + old_memcg = memalloc_use_memcg(group->memcg); event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL); - memalloc_unuse_memcg(); + memalloc_use_memcg(old_memcg); if (unlikely(!event)) { /* diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index f889e332912f..b8fde48d44a9 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -312,31 +312,21 @@ static inline void memalloc_nocma_restore(unsigned int flags) * __GFP_ACCOUNT allocations till the end of the scope will be charged to the * given memcg. * - * NOTE: This function is not nesting safe. + * NOTE: This function can nest. Users must save the return value and + * reset the previous value after their own charging scope is over */ -static inline void memalloc_use_memcg(struct mem_cgroup *memcg) +static inline struct mem_cgroup * +memalloc_use_memcg(struct mem_cgroup *memcg) { - WARN_ON_ONCE(current->active_memcg); + struct mem_cgroup *old = current->active_memcg; current->active_memcg = memcg; -} - -/** - * memalloc_unuse_memcg - Ends the remote memcg charging scope. - * - * This function marks the end of the remote memcg charging scope started by - * memalloc_use_memcg(). - */ -static inline void memalloc_unuse_memcg(void) -{ - current->active_memcg = NULL; + return old; } #else -static inline void memalloc_use_memcg(struct mem_cgroup *memcg) -{ -} - -static inline void memalloc_unuse_memcg(void) +static inline struct mem_cgroup * +memalloc_use_memcg(struct mem_cgroup *memcg) { + return NULL; } #endif diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b807952b4d43..b2468c80085d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5271,12 +5271,12 @@ static struct cgroup_subsys_state * __ref mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) { struct mem_cgroup *parent = mem_cgroup_from_css(parent_css); - struct mem_cgroup *memcg; + struct mem_cgroup *memcg, *old_memcg; long error = -ENOMEM; - memalloc_use_memcg(parent); + old_memcg = memalloc_use_memcg(parent); memcg = mem_cgroup_alloc(); - memalloc_unuse_memcg(); + memalloc_use_memcg(old_memcg); if (IS_ERR(memcg)) return ERR_CAST(memcg);