From: Binder Makin merimus@google.com

maillist inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7VO77

--------------------------------

Add a lockless resource controller for limiting the number of open file handles. This allows us to catch misbehaving processes and return EMFILE instead of ENOMEM for kernel memory limits.

Original link: https://lwn.net/Articles/604129/.After introduced https://gitlab.indel.ch/thirdparty/linux-indel/commit /5b1efc027c0b51ca3e76f4e00c83358f8349f543. All memory accounting and limiting has been switched over to the lockless page counters. So we convert original resource counters to lockless page counters.

Signed-off-by: Binder Makin merimus@google.com Reviewed-by: Qiang Huang h.huangqiang@huawei.com [cm: convert to lockless page counters] Conflict: fs/Makefile include/linux/cgroup.h Signed-off-by: Lu Jialin lujialin4@huawei.com --- fs/Makefile | 1 + fs/file.c | 53 +++++- fs/filescontrol.c | 321 ++++++++++++++++++++++++++++++++++ include/linux/cgroup-defs.h | 8 +- include/linux/cgroup.h | 6 + include/linux/cgroup_subsys.h | 6 + include/linux/fdtable.h | 1 + include/linux/filescontrol.h | 34 ++++ init/Kconfig | 10 ++ 9 files changed, 435 insertions(+), 5 deletions(-) create mode 100644 fs/filescontrol.c create mode 100644 include/linux/filescontrol.h

diff --git a/fs/Makefile b/fs/Makefile index 5bfdbf0d7037..5030041ea469 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -52,6 +52,7 @@ obj-$(CONFIG_COREDUMP) += coredump.o obj-$(CONFIG_SYSCTL) += drop_caches.o sysctls.o

obj-$(CONFIG_FHANDLE) += fhandle.o +obj-$(CONFIG_CGROUP_FILES) += filescontrol.o obj-y += iomap/

obj-y += quota/ diff --git a/fs/file.c b/fs/file.c index 7893ea161d77..68f5c936a236 100644 --- a/fs/file.c +++ b/fs/file.c @@ -19,6 +19,7 @@ #include <linux/bitops.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <linux/filescontrol.h> #include <linux/close_range.h> #include <net/sock.h>

@@ -337,6 +338,9 @@ struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int new_fdt->open_fds = newf->open_fds_init; new_fdt->full_fds_bits = newf->full_fds_bits_init; new_fdt->fd = &newf->fd_array[0]; +#ifdef CONFIG_CGROUP_FILES + files_cgroup_assign(newf); +#endif

spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); @@ -400,10 +404,29 @@ struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *));

rcu_assign_pointer(newf->fdt, new_fdt); +#ifdef CONFIG_CGROUP_FILES + if (!files_cgroup_alloc_fd(newf, files_cgroup_count_fds(newf))) + return newf; + +/* could not get enough FD resources. Need to clean up. */ + new_fds = new_fdt->fd; + for (i = open_files; i != 0; i--) { + struct file *f = *new_fds++;

+ if (f) + fput(f); + } + if (new_fdt != &newf->fdtab) + __free_fdtable(new_fdt); + *errorp = -EMFILE; +#else return newf; +#endif

out_release: +#ifdef CONFIG_CGROUP_FILES + files_cgroup_remove(newf); +#endif kmem_cache_free(files_cachep, newf); out: return NULL; @@ -429,6 +452,9 @@ static struct fdtable *close_files(struct files_struct * files) if (set & 1) { struct file * file = xchg(&fdt->fd[i], NULL); if (file) { +#ifdef CONFIG_CGROUP_FILES + files_cgroup_unalloc_fd(files, 1); +#endif filp_close(file, files); cond_resched(); } @@ -531,6 +557,12 @@ static int alloc_fd(unsigned start, unsigned end, unsigned flags) */ if (error) goto repeat; +#ifdef CONFIG_CGROUP_FILES + if (files_cgroup_alloc_fd(files, 1)) { + error = -EMFILE; + goto out; + } +#endif

if (start <= files->next_fd) files->next_fd = fd + 1; @@ -568,6 +600,10 @@ EXPORT_SYMBOL(get_unused_fd_flags); static void __put_unused_fd(struct files_struct *files, unsigned int fd) { struct fdtable *fdt = files_fdtable(files); +#ifdef CONFIG_CGROUP_FILES + if (test_bit(fd, fdt->open_fds)) + files_cgroup_unalloc_fd(files, 1); +#endif __clear_open_fd(fd, fdt); if (fd < files->next_fd) files->next_fd = fd; @@ -1090,6 +1126,7 @@ static int do_dup2(struct files_struct *files, struct file *file, unsigned fd, unsigned flags) __releases(&files->file_lock) { + int err; struct file *tofree; struct fdtable *fdt;

@@ -1109,8 +1146,16 @@ __releases(&files->file_lock) */ fdt = files_fdtable(files); tofree = fdt->fd[fd]; - if (!tofree && fd_is_open(fd, fdt)) - goto Ebusy; + if (!tofree && fd_is_open(fd, fdt)) { + err = -EBUSY; + goto out; + } +#ifdef CONFIG_CGROUP_FILES + if (!tofree && files_cgroup_alloc_fd(files, 1)) { + err = -EMFILE; + goto out; + } +#endif get_file(file); rcu_assign_pointer(fdt->fd[fd], file); __set_open_fd(fd, fdt); @@ -1125,9 +1170,9 @@ __releases(&files->file_lock)

return fd;

-Ebusy: +out: spin_unlock(&files->file_lock); - return -EBUSY; + return err; }

int replace_fd(unsigned fd, struct file *file, unsigned flags) diff --git a/fs/filescontrol.c b/fs/filescontrol.c new file mode 100644 index 000000000000..44ad9ef44e20 --- /dev/null +++ b/fs/filescontrol.c @@ -0,0 +1,321 @@ +// SPDX-License-Identifier: GPL-2.0 +/* filescontrol.c - Cgroup controller for open file handles. + * + * Copyright 2014 Google Inc. + * Author: Brian Makin merimus@google.com + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/page_counter.h> +#include <linux/filescontrol.h> +#include <linux/cgroup.h> +#include <linux/export.h> +#include <linux/printk.h> +#include <linux/slab.h> +#include <linux/fs.h> +#include <linux/seq_file.h> +#include <linux/fdtable.h> +#include <linux/sched/signal.h> + +#define FILES_MAX ULLONG_MAX +#define FILES_MAX_STR "max" + + +struct cgroup_subsys files_cgrp_subsys __read_mostly; +EXPORT_SYMBOL(files_cgrp_subsys); + +struct files_cgroup { + struct cgroup_subsys_state css; + struct page_counter open_handles; +}; + +static inline struct files_cgroup *css_fcg(struct cgroup_subsys_state *css) +{ + return css ? container_of(css, struct files_cgroup, css) : NULL; +} + +static inline struct page_counter * +css_res_open_handles(struct cgroup_subsys_state *css) +{ + return &css_fcg(css)->open_handles; +} + +static inline struct files_cgroup * +files_cgroup_from_files(struct files_struct *files) +{ + return files->files_cgroup; +} + + +static struct cgroup_subsys_state * +files_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) +{ + struct files_cgroup *parent_fcg; + struct files_cgroup *fcg; + + parent_fcg = css_fcg(parent_css); + fcg = kzalloc(sizeof(*fcg), GFP_KERNEL); + if (!fcg) + goto out; + + if (!parent_fcg) { + page_counter_init(&fcg->open_handles, NULL); + page_counter_set_max(&fcg->open_handles, FILES_MAX); + } else { + struct page_counter *p_counter = &parent_fcg->open_handles; + + page_counter_init(&fcg->open_handles, p_counter); + page_counter_set_max(&fcg->open_handles, FILES_MAX); + } + return &fcg->css; + +out: + return ERR_PTR(-ENOMEM); +} + +static void files_cgroup_css_free(struct cgroup_subsys_state *css) +{ + kfree(css_fcg(css)); +} + +u64 files_cgroup_count_fds(struct files_struct *files) +{ + int i; + struct fdtable *fdt; + int retval = 0; + + fdt = files_fdtable(files); + for (i = 0; i < DIV_ROUND_UP(fdt->max_fds, BITS_PER_LONG); i++) + retval += hweight64((__u64)fdt->open_fds[i]); + return retval; +} + +static u64 files_in_taskset(struct cgroup_taskset *tset) +{ + struct task_struct *task; + u64 files = 0; + struct cgroup_subsys_state *css; + + cgroup_taskset_for_each(task, css, tset) { + if (!thread_group_leader(task)) + continue; + + task_lock(task); + files += files_cgroup_count_fds(task->files); + task_unlock(task); + } + return files; +} + +/* + * If attaching this cgroup would overcommit the resource then deny + * the attach. + */ +static int files_cgroup_can_attach(struct cgroup_taskset *tset) +{ + struct cgroup_subsys_state *css; + unsigned long margin; + struct page_counter *cnt; + unsigned long counter; + u64 files = files_in_taskset(tset); + + cgroup_taskset_first(tset, &css); + cnt = css_res_open_handles(css); + + counter = (unsigned long)atomic_long_read(&cnt->usage); + if (cnt->max > counter) + margin = cnt->max - counter; + else + margin = 0; + if (margin < files) + return -ENOMEM; + return 0; +} + +/* + * If resource counts have gone up between can_attach and attach then + * this may overcommit resources. In that case just deny further allocation + * until the resource usage drops. + */ +static void files_cgroup_attach(struct cgroup_taskset *tset) +{ + u64 num_files; + struct cgroup_subsys_state *to_css; + struct cgroup_subsys_state *from_css; + struct page_counter *from_res; + struct page_counter *to_res; + struct page_counter *fail_res; + struct files_struct *files; + struct task_struct *task = cgroup_taskset_first(tset, &to_css); + + to_res = css_res_open_handles(to_css); + + task_lock(task); + files = task->files; + if (!files) { + task_unlock(task); + return; + } + + from_css = &files_cgroup_from_files(files)->css; + from_res = css_res_open_handles(from_css); + + spin_lock(&files->file_lock); + num_files = files_cgroup_count_fds(files); + page_counter_uncharge(from_res, num_files); + css_put(from_css); + + if (!page_counter_try_charge(to_res, num_files, &fail_res)) + pr_err("Open files limit overcommited\n"); + css_get(to_css); + task->files->files_cgroup = css_fcg(to_css); + spin_unlock(&files->file_lock); + task_unlock(task); +} + +int files_cgroup_alloc_fd(struct files_struct *files, u64 n) +{ + /* + * Kernel threads which are forked by kthreadd inherited the + * const files_struct 'init_files', we didn't wrap it so + * there's no associated files_cgroup. + * + * Kernel threads always stay in root cgroup, and we don't + * have limit for root files cgroup, so it won't hurt if + * we don't charge their fds, only issue is that files.usage + * won't be accurate in root files cgroup. + */ + if (files != &init_files) { + struct page_counter *fail_res; + struct files_cgroup *files_cgroup = + files_cgroup_from_files(files); + if (!page_counter_try_charge(&files_cgroup->open_handles, + n, &fail_res)) + return -ENOMEM; + } + return 0; +} +EXPORT_SYMBOL(files_cgroup_alloc_fd); + +void files_cgroup_unalloc_fd(struct files_struct *files, u64 n) +{ + /* + * It's not charged so no need to uncharge, see comments in + * files_cgroup_alloc_fd. + */ + if (files != &init_files) { + struct files_cgroup *files_cgroup = + files_cgroup_from_files(files); + page_counter_uncharge(&files_cgroup->open_handles, n); + } +} +EXPORT_SYMBOL(files_cgroup_unalloc_fd); + + +static int files_limit_read(struct seq_file *sf, void *v) +{ + struct files_cgroup *fcg = css_fcg(seq_css(sf)); + struct page_counter *counter = &fcg->open_handles; + u64 limit = counter->max; + + if (limit >= FILES_MAX) + seq_printf(sf, "%s\n", FILES_MAX_STR); + else + seq_printf(sf, "%llu\n", limit); + + return 0; +} + +static ssize_t files_limit_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + struct files_cgroup *fcg = css_fcg(of_css(of)); + u64 limit; + int err; + + buf = strstrip((char *)buf); + if (!strcmp(buf, FILES_MAX_STR)) { + limit = FILES_MAX; + goto set_limit; + } + + err = kstrtoull(buf, 0, &limit); + if (err) + return err; + +set_limit: + /* + * Limit updates don't need to be mutex'd, since it isn't + * critical that any racing fork()s follow the new limit. + */ + page_counter_set_max(&fcg->open_handles, limit); + return nbytes; +} + + +static u64 files_usage_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + struct files_cgroup *fcg = css_fcg(css); + + return page_counter_read(&fcg->open_handles); +} + +static struct cftype files[] = { + { + .name = "limit", + .seq_show = files_limit_read, + .write = files_limit_write, + .flags = CFTYPE_NOT_ON_ROOT, + }, + { + .name = "usage", + .read_u64 = files_usage_read, + }, + { } +}; + +struct cgroup_subsys files_cgrp_subsys = { + .css_alloc = files_cgroup_css_alloc, + .css_free = files_cgroup_css_free, + .can_attach = files_cgroup_can_attach, + .attach = files_cgroup_attach, + .legacy_cftypes = files, + .dfl_cftypes = files, +}; + +void files_cgroup_assign(struct files_struct *files) +{ + struct task_struct *tsk = current; + struct cgroup_subsys_state *css; + struct cgroup *cgrp; + + task_lock(tsk); + cgrp = task_cgroup(tsk, files_cgrp_id); + css = cgroup_subsys_state(cgrp, files_cgrp_id); + css_get(css); + files->files_cgroup = container_of(css, struct files_cgroup, css); + task_unlock(tsk); +} + +void files_cgroup_remove(struct files_struct *files) +{ + struct task_struct *tsk = current; + struct files_cgroup *fcg; + + task_lock(tsk); + spin_lock(&files->file_lock); + fcg = files_cgroup_from_files(files); + css_put(&fcg->css); + spin_unlock(&files->file_lock); + task_unlock(tsk); +} diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 8a0d5466c7be..844ccf4187ed 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -639,6 +639,12 @@ struct cftype { ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off);

+ int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, + struct seq_file *m); + + int (*write_string)(struct cgroup *cgrp, struct cftype *cft, + const char *buffer); + __poll_t (*poll)(struct kernfs_open_file *of, struct poll_table_struct *pt);

@@ -726,7 +732,7 @@ struct cgroup_subsys { */ struct cftype *dfl_cftypes; /* for the default hierarchy */ struct cftype *legacy_cftypes; /* for the legacy hierarchies */ - + struct cftype *base_cftypes; /* * A subsystem may depend on other subsystems. When such subsystem * is enabled on a cgroup, the depended-upon subsystems are enabled diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 885f5395fcd0..40b67ca53719 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -363,6 +363,12 @@ static inline void cgroup_put(struct cgroup *cgrp) css_put(&cgrp->self); }

+static inline struct cgroup_subsys_state *cgroup_subsys_state( + struct cgroup *cgrp, int subsys_id) +{ + return cgrp->subsys[subsys_id]; +} + extern struct mutex cgroup_mutex;

static inline void cgroup_lock(void) diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h index 445235487230..f57184cad7f6 100644 --- a/include/linux/cgroup_subsys.h +++ b/include/linux/cgroup_subsys.h @@ -72,6 +72,12 @@ SUBSYS(misc) SUBSYS(debug) #endif

+#if IS_ENABLED(CONFIG_CGROUP_FILES) +SUBSYS(files) +#endif + /* * DO NOT ADD ANY SUBSYSTEM WITHOUT EXPLICIT ACKS FROM CGROUP MAINTAINERS. */ + + diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index e066816f3519..22b8b03fef6d 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -65,6 +65,7 @@ struct files_struct { unsigned long open_fds_init[1]; unsigned long full_fds_bits_init[1]; struct file __rcu * fd_array[NR_OPEN_DEFAULT]; + struct files_cgroup *files_cgroup; };

struct file_operations; diff --git a/include/linux/filescontrol.h b/include/linux/filescontrol.h new file mode 100644 index 000000000000..49dc620cf64e --- /dev/null +++ b/include/linux/filescontrol.h @@ -0,0 +1,34 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* filescontrol.h - Files Controller + * + * Copyright 2014 Google Inc. + * Author: Brian Makin merimus@google.com + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#ifndef _LINUX_FILESCONTROL_H +#define _LINUX_FILESCONTROL_H + +#include <linux/fdtable.h> + +#ifdef CONFIG_CGROUP_FILES + +extern int files_cgroup_alloc_fd(struct files_struct *files, u64 n); +extern void files_cgroup_unalloc_fd(struct files_struct *files, u64 n); +extern u64 files_cgroup_count_fds(struct files_struct *files); +extern struct files_struct init_files; + +void files_cgroup_assign(struct files_struct *files); +void files_cgroup_remove(struct files_struct *files); + +#endif /* CONFIG_CGROUP_FILES */ +#endif /* _LINUX_FILESCONTROL_H */ diff --git a/init/Kconfig b/init/Kconfig index 32c24950c4ce..bec1cba111c5 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1174,6 +1174,16 @@ config SOCK_CGROUP_DATA bool default n

+config CGROUP_FILES + bool "Files Resource Controller for Control Groups" + select PAGE_COUNTER + default n + help + Provides a cgroup resource controller that limits number of open + file handles within a cgroup. + This supports catching misbehaving processes and + return EMFILE instead of ENOMEM for kernel memory limits. + endif # CGROUPS

menuconfig NAMESPACES

From: Yu Kuai yukuai3@huawei.com

hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7VO77

--------------------------------

Such switch can only set the accounting of open fds in filescontrol from enable to disable. If it is disabled arealdy, the switch can't enable it.

The counter is enabled by default, and it can be disabled by: a. echo 1 > /sys/fs/cgroup/files/files.no_acct b. add "filescontrol.no_acct=1" to boot cmd

Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: Hou Tao houtao1@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Lu Jialin lujialin4@huawei.com --- fs/filescontrol.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/fs/filescontrol.c b/fs/filescontrol.c index 1d2d29127fd4..a24be705f621 100644 --- a/fs/filescontrol.c +++ b/fs/filescontrol.c @@ -25,14 +25,17 @@ #include <linux/seq_file.h> #include <linux/fdtable.h> #include <linux/sched/signal.h> +#include <linux/module.h>

#define FILES_MAX ULLONG_MAX #define FILES_MAX_STR "max"

- +static bool no_acct; struct cgroup_subsys files_cgrp_subsys __read_mostly; EXPORT_SYMBOL(files_cgrp_subsys);

+module_param(no_acct, bool, 0444); + struct files_cgroup { struct cgroup_subsys_state css; struct page_counter open_handles; @@ -194,7 +197,7 @@ int files_cgroup_alloc_fd(struct files_struct *files, u64 n) * we don't charge their fds, only issue is that files.usage * won't be accurate in root files cgroup. */ - if (files != &init_files) { + if (!no_acct && files != &init_files) { struct page_counter *fail_res; struct files_cgroup *files_cgroup = files_cgroup_from_files(files); @@ -212,7 +215,7 @@ void files_cgroup_unalloc_fd(struct files_struct *files, u64 n) * It's not charged so no need to uncharge, see comments in * files_cgroup_alloc_fd. */ - if (files != &init_files) { + if (!no_acct && files != &init_files) { struct files_cgroup *files_cgroup = files_cgroup_from_files(files); page_counter_uncharge(&files_cgroup->open_handles, n); @@ -220,6 +223,21 @@ void files_cgroup_unalloc_fd(struct files_struct *files, u64 n) } EXPORT_SYMBOL(files_cgroup_unalloc_fd);

+static u64 files_disabled_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + return no_acct; +} + +static int files_disabled_write(struct cgroup_subsys_state *css, + struct cftype *cft, u64 val) +{ + if (!val) + return -EINVAL; + no_acct = true; + + return 0; +}

static int files_limit_read(struct seq_file *sf, void *v) { @@ -281,6 +299,12 @@ static struct cftype files[] = { .name = "usage", .read_u64 = files_usage_read, }, + { + .name = "no_acct", + .flags = CFTYPE_ONLY_ON_ROOT, + .read_u64 = files_disabled_read, + .write_u64 = files_disabled_write, + }, { } };

hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7VO77

--------------------------------

If parent cgroup files.limit is 0, fail to move a task into child cgroup. When kill the task, the files.usage of parent cgroup and child cgroup is abnormal.

/sys/fs/cgroup/parent # ls cgroup.clone_children files.limit tasks cgroup.procs files.usage child notify_on_release /sys/fs/cgroup/parent # echo 0 >files.limit /sys/fs/cgroup/parent # cd child /sys/fs/cgroup/parent/child # ls cgroup.clone_children files.limit notify_on_release cgroup.procs files.usage tasks /sys/fs/cgroup/parent/child # echo 156 >tasks [ 879.564728] Open files limit overcommited /sys/fs/cgroup/parent/child # kill -9 156 /sys/fs/cgroup/parent/child # [ 886.363690] WARNING: CPU: 0 PID: 156 at mm/page_counter.c:62 page_counter_cancel+0x26/0x30 [ 886.364093] Modules linked in: [ 886.364093] CPU: 0 PID: 156 Comm: top Not tainted 4.18.0+ #1 [ 886.364093] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 [ 886.365350] RIP: 0010:page_counter_cancel+0x26/0x30 [ 886.365350] Code: 0f 1f 40 00 66 66 66 66 90 48 89 f0 53 48 f7 d8 f0 48 0f c1 07 48 29 f0 48 89 c3 48 89 c6 e8 61 ff ff ff 48 85 d5 [ 886.365350] RSP: 0018:ffffb754006b7d00 EFLAGS: 00000286 [ 886.365350] RAX: 0000000000000000 RBX: ffffffffffffffff RCX: 0000000000000001 [ 886.365350] RDX: 0000000000000000 RSI: ffffffffffffffff RDI: ffff9ca61888b930 [ 886.365350] RBP: 0000000000000001 R08: 00000000000295c0 R09: ffffffff820597aa [ 886.365350] R10: ffffffffffffffff R11: ffffd78601823508 R12: 0000000000000000 [ 886.365350] R13: ffff9ca6181c0628 R14: 0000000000000000 R15: ffff9ca663e9d000 [ 886.365350] FS: 0000000000000000(0000) GS:ffff9ca661e00000(0000) knlGS:0000000000000000 [ 886.365350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 886.365350] CR2: 0000000000867fb8 CR3: 0000000017a0a000 CR4: 00000000000006f0 [ 886.365350] Call Trace: [ 886.369392] page_counter_uncharge+0x1d/0x30 [ 886.369392] put_files_struct+0x7c/0xe0 [ 886.369392] do_exit+0x2c7/0xb90 [ 886.369392] ? __schedule+0x2a1/0x900 [ 886.369392] do_group_exit+0x3a/0xa0 [ 886.369392] get_signal+0x15e/0x870 [ 886.369392] do_signal+0x36/0x610 [ 886.369392] ? do_vfs_ioctl+0xa4/0x640 [ 886.369392] ? do_vfs_ioctl+0xa4/0x640 [ 886.369392] ? dput+0x29/0x110 [ 886.369392] exit_to_usermode_loop+0x71/0xe0 [ 886.369392] do_syscall_64+0x181/0x1b0 [ 886.369392] entry_SYSCALL_64_after_hwframe+0x65/0xca [ 886.369392] RIP: 0033:0x4b9b5a [ 886.369392] Code: Bad RIP value. [ 886.369392] RSP: 002b:00007ffe27221968 EFLAGS: 00000206 ORIG_RAX: 0000000000000010 [ 886.373373] RAX: fffffffffffffe00 RBX: 0000000000000001 RCX: 00000000004b9b5a [ 886.373373] RDX: 00007ffe27221930 RSI: 0000000000005402 RDI: 0000000000000000 [ 886.373373] RBP: 0000000000000135 R08: 00007ffe272219a4 R09: 0000000000000010 [ 886.373373] R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 [ 886.373373] R13: 0000000000000005 R14: 0000000000000135 R15: 0000000000000000 [ 886.373373] ---[ end trace 56c4971a753a98c5 ]---

[1]+ Killed top /sys/fs/cgroup/parent/child # ls cgroup.clone_children files.limit notify_on_release cgroup.procs files.usage tasks /sys/fs/cgroup/parent/child # cat files.usage 18446744073709551613 /sys/fs/cgroup/parent/child # cd .. /sys/fs/cgroup/parent # ls cgroup.clone_children files.limit tasks cgroup.procs files.usage child notify_on_release /sys/fs/cgroup/parent # cat files.usage 18446744073709551613

The reason is when fail to move a task into child cgroup,the files.usage of child cgroup and its parent cgroup are the same as before. The struct files_cgroup points to the dst_css. Therefore, when kill the task, the page_counter_uncharge() will subtract the files.usage of child cgroup and its parent cgroup again. The files.usage will be abnormal.

If we just change the struct files_cgroup pointers when charge success in files_cgroup_attach, problems will occur in some extreme scenario. 1)If we add num_files into original page_counter when fail to charge the file resource into new cgroup, the files.usage will be larger than files.limit of the original cgroup when new task moves into the original cgroup at the same time. 2)If we subtract num_files into original page_counter when success to charge the file resource into new cgroup, when the parent files.limit equals to the files.usage and there are two child cgroups of the parent, it will be failed to move the task from one child cgroup into another child cgroup.

The patch implements files_cgroup_attach() into files_cgroup_can_attach() and delete files_cgroup_attach(). This will make move file related resource into new cgroup before move task. When try_charge is failed, task and its file resource will be in the original cgroup.The above problems will be solved.

Signed-off-by: Lu Jialin lujialin4@huawei.com --- fs/filescontrol.c | 63 ++++++++++------------------------------------- 1 file changed, 13 insertions(+), 50 deletions(-)

diff --git a/fs/filescontrol.c b/fs/filescontrol.c index db0beee474b2..41abe29fc0f8 100644 --- a/fs/filescontrol.c +++ b/fs/filescontrol.c @@ -102,56 +102,14 @@ u64 files_cgroup_count_fds(struct files_struct *files) return retval; }

-static u64 files_in_taskset(struct cgroup_taskset *tset) -{ - struct task_struct *task; - u64 files = 0; - struct cgroup_subsys_state *css; - - cgroup_taskset_for_each(task, css, tset) { - if (!thread_group_leader(task)) - continue; - - task_lock(task); - files += files_cgroup_count_fds(task->files); - task_unlock(task); - } - return files; -} - /* * If attaching this cgroup would overcommit the resource then deny - * the attach. + * the attach. If not, attach the file resource into new cgroup. */ static int files_cgroup_can_attach(struct cgroup_taskset *tset) -{ - struct cgroup_subsys_state *css; - unsigned long margin; - struct page_counter *cnt; - unsigned long counter; - u64 files = files_in_taskset(tset); - - cgroup_taskset_first(tset, &css); - cnt = css_res_open_handles(css); - - counter = (unsigned long)atomic_long_read(&cnt->usage); - if (cnt->max > counter) - margin = cnt->max - counter; - else - margin = 0; - if (margin < files) - return -ENOMEM; - return 0; -} - -/* - * If resource counts have gone up between can_attach and attach then - * this may overcommit resources. In that case just deny further allocation - * until the resource usage drops. - */ -static void files_cgroup_attach(struct cgroup_taskset *tset) { u64 num_files; + bool can_attach; struct cgroup_subsys_state *to_css; struct cgroup_subsys_state *from_css; struct page_counter *from_res; @@ -166,7 +124,7 @@ static void files_cgroup_attach(struct cgroup_taskset *tset) files = task->files; if (!files || files == &init_files) { task_unlock(task); - return; + return 0; }

from_css = &files_cgroup_from_files(files)->css; @@ -175,14 +133,20 @@ static void files_cgroup_attach(struct cgroup_taskset *tset) spin_lock(&files->file_lock); num_files = files_cgroup_count_fds(files); page_counter_uncharge(from_res, num_files); - css_put(from_css);

- if (!page_counter_try_charge(to_res, num_files, &fail_res)) + if (!page_counter_try_charge(to_res, num_files, &fail_res)) { + page_counter_charge(from_res, num_files); pr_err("Open files limit overcommited\n"); - css_get(to_css); - task->files->files_cgroup = css_fcg(to_css); + can_attach = false; + } else { + css_put(from_css); + css_get(to_css); + task->files->files_cgroup = css_fcg(to_css); + can_attach = true; + } spin_unlock(&files->file_lock); task_unlock(task); + return can_attach ? 0 : -ENOSPC; }

int files_cgroup_alloc_fd(struct files_struct *files, u64 n) @@ -312,7 +276,6 @@ struct cgroup_subsys files_cgrp_subsys = { .css_alloc = files_cgroup_css_alloc, .css_free = files_cgroup_css_free, .can_attach = files_cgroup_can_attach, - .attach = files_cgroup_attach, .legacy_cftypes = files, .dfl_cftypes = files, };

From: yangerkun yangerkun@huawei.com

hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7VO77

--------------------------------

We use lockref for dentry reference without notice that so many negative dentry under one dir can lead to overflow of lockref. This can lead to system crash if we do this under root dir.

Since there is not a perfect solution, we just limit max number of dentry count up to INT_MAX / 2. Also, it will cost a lot of time from INT_MAX / 2 to INT_MAX, so we no need to do this under protection of dentry lock.

Also, we limit the FILES_MAX to INT_MAX / 2, since a lot open for same file can lead to overflow too.

Changelog: v1->v2: add a function to do check / add a Macro to mean INT_MAX / 2

Signed-off-by: yangerkun yangerkun@huawei.com Reviewed-by: Miao Xie miaoxie@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com

Conflicts: fs/dcache.c Reviewed-by: Zhang Yi yi.zhang@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Signed-off-by: Lu Jialin lujialin4@huawei.com --- fs/dcache.c | 32 ++++++++++++++++++++++++++++---- fs/filescontrol.c | 2 +- include/linux/fs.h | 3 +++ 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c index 52e6d5fdab6b..988f763bda78 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1835,6 +1835,18 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) return dentry; }

+static inline bool d_forbid_overflow(struct dentry *dentry) +{ + if (unlikely(d_count(dentry) >= D_COUNT_MAX)) { + shrink_dcache_parent(dentry); + + if (d_count(dentry) >= D_COUNT_MAX) + return false; + } + + return true; +} + /** * d_alloc - allocate a dcache entry * @parent: parent of entry to allocate @@ -1846,9 +1858,15 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) */ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) { - struct dentry *dentry = __d_alloc(parent->d_sb, name); + struct dentry *dentry = NULL; + + if (unlikely(!d_forbid_overflow(parent))) + goto out; + + dentry = __d_alloc(parent->d_sb, name); if (!dentry) - return NULL; + goto out; + spin_lock(&parent->d_lock); /* * don't need child lock because it is not subject @@ -1858,7 +1876,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) dentry->d_parent = parent; list_add(&dentry->d_child, &parent->d_subdirs); spin_unlock(&parent->d_lock); - +out: return dentry; } EXPORT_SYMBOL(d_alloc); @@ -1871,11 +1889,17 @@ EXPORT_SYMBOL(d_alloc_anon);

struct dentry *d_alloc_cursor(struct dentry * parent) { - struct dentry *dentry = d_alloc_anon(parent->d_sb); + struct dentry *dentry = NULL; + + if (unlikely(!d_forbid_overflow(parent))) + goto out; + + dentry = d_alloc_anon(parent->d_sb); if (dentry) { dentry->d_flags |= DCACHE_DENTRY_CURSOR; dentry->d_parent = dget(parent); } +out: return dentry; }

diff --git a/fs/filescontrol.c b/fs/filescontrol.c index 4ad500f40025..fdd557a246be 100644 --- a/fs/filescontrol.c +++ b/fs/filescontrol.c @@ -27,7 +27,7 @@ #include <linux/sched/signal.h> #include <linux/module.h>

-#define FILES_MAX ULONG_MAX +#define FILES_MAX D_COUNT_MAX #define FILES_MAX_STR "max"

static bool no_acct; diff --git a/include/linux/fs.h b/include/linux/fs.h index 133f0640fb24..2921f5d65b62 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -47,6 +47,9 @@ #include <asm/byteorder.h> #include <uapi/linux/fs.h>

+#define D_COUNT_MAX (INT_MAX / 2) + + struct backing_dev_info; struct bdi_writeback; struct bio;