epoll: introduce resource usage limits (7ef9964e) · Commits · e / devices / android_kernel_oneplus_sm7250

Documentation/filesystems/proc.txt

+27 −0

Original line number	Original line	Diff line number	Diff line
	@@ -44,6 +44,7 @@ Table of Contents
	2.14 /proc/<pid>/io - Display the IO accounting fields		2.14 /proc/<pid>/io - Display the IO accounting fields
	2.15 /proc/<pid>/coredump_filter - Core dump filtering settings		2.15 /proc/<pid>/coredump_filter - Core dump filtering settings
	2.16 /proc/<pid>/mountinfo - Information about mounts		2.16 /proc/<pid>/mountinfo - Information about mounts
			2.17 /proc/sys/fs/epoll - Configuration options for the epoll interface

	------------------------------------------------------------------------------		------------------------------------------------------------------------------
	Preface		Preface
	@@ -2483,4 +2484,30 @@ For more information on mount propagation see:

	Documentation/filesystems/sharedsubtree.txt		Documentation/filesystems/sharedsubtree.txt

			2.17 /proc/sys/fs/epoll - Configuration options for the epoll interface
			--------------------------------------------------------

			This directory contains configuration options for the epoll(7) interface.

			max_user_instances
			------------------

			This is the maximum number of epoll file descriptors that a single user can
			have open at a given time. The default value is 128, and should be enough
			for normal users.

			max_user_watches
			----------------

			Every epoll file descriptor can store a number of files to be monitored
			for event readiness. Each one of these monitored files constitutes a "watch".
			This configuration option sets the maximum number of "watches" that are
			allowed for each user.
			Each "watch" costs roughly 90 bytes on a 32bit kernel, and roughly 160 bytes
			on a 64bit one.
			The current default value for max_user_watches is the 1/32 of the available
			low memory, divided for the "watch" cost in bytes.


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

fs/eventpoll.c

+77 −8

Original line number	Original line	Diff line number	Diff line
	@@ -102,6 +102,8 @@

	#define EP_UNACTIVE_PTR ((void *) -1L)		#define EP_UNACTIVE_PTR ((void *) -1L)

			#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))

	struct epoll_filefd {		struct epoll_filefd {
	struct file *file;		struct file *file;
	int fd;		int fd;
	@@ -200,6 +202,9 @@ struct eventpoll {
	* holding ->lock.		* holding ->lock.
	*/		*/
	struct epitem *ovflist;		struct epitem *ovflist;

			/* The user that created the eventpoll descriptor */
			struct user_struct *user;
	};		};

	/* Wait structure used by the poll hooks */		/* Wait structure used by the poll hooks */
	@@ -226,10 +231,18 @@ struct ep_pqueue {
	struct epitem *epi;		struct epitem *epi;
	};		};

			/*
			* Configuration options available inside /proc/sys/fs/epoll/
			*/
			/* Maximum number of epoll devices, per user */
			static int max_user_instances __read_mostly;
			/* Maximum number of epoll watched descriptors, per user */
			static int max_user_watches __read_mostly;

	/*		/*
	* This mutex is used to serialize ep_free() and eventpoll_release_file().		* This mutex is used to serialize ep_free() and eventpoll_release_file().
	*/		*/
	static struct mutex epmutex;		static DEFINE_MUTEX(epmutex);

	/* Safe wake up implementation */		/* Safe wake up implementation */
	static struct poll_safewake psw;		static struct poll_safewake psw;
	@@ -240,6 +253,33 @@ static struct kmem_cache *epi_cache __read_mostly;
	/* Slab cache used to allocate "struct eppoll_entry" */		/* Slab cache used to allocate "struct eppoll_entry" */
	static struct kmem_cache *pwq_cache __read_mostly;		static struct kmem_cache *pwq_cache __read_mostly;

			#ifdef CONFIG_SYSCTL

			#include <linux/sysctl.h>

			static int zero;

			ctl_table epoll_table[] = {
			{
			.procname = "max_user_instances",
			.data = &max_user_instances,
			.maxlen = sizeof(int),
			.mode = 0644,
			.proc_handler = &proc_dointvec_minmax,
			.extra1 = &zero,
			},
			{
			.procname = "max_user_watches",
			.data = &max_user_watches,
			.maxlen = sizeof(int),
			.mode = 0644,
			.proc_handler = &proc_dointvec_minmax,
			.extra1 = &zero,
			},
			{ .ctl_name = 0 }
			};
			#endif /* CONFIG_SYSCTL */


	/* Setup the structure that is used as key for the RB tree */		/* Setup the structure that is used as key for the RB tree */
	static inline void ep_set_ffd(struct epoll_filefd *ffd,		static inline void ep_set_ffd(struct epoll_filefd *ffd,
	@@ -402,6 +442,8 @@ static int ep_remove(struct eventpoll ep, struct epitem epi)
	/* At this point it is safe to free the eventpoll item */		/* At this point it is safe to free the eventpoll item */
	kmem_cache_free(epi_cache, epi);		kmem_cache_free(epi_cache, epi);

			atomic_dec(&ep->user->epoll_watches);

	DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p)\n",		DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p)\n",
	current, ep, file));		current, ep, file));

	@@ -449,6 +491,8 @@ static void ep_free(struct eventpoll *ep)

	mutex_unlock(&epmutex);		mutex_unlock(&epmutex);
	mutex_destroy(&ep->mtx);		mutex_destroy(&ep->mtx);
			atomic_dec(&ep->user->epoll_devs);
			free_uid(ep->user);
	kfree(ep);		kfree(ep);
	}		}

	@@ -532,10 +576,19 @@ void eventpoll_release_file(struct file *file)

	static int ep_alloc(struct eventpoll **pep)		static int ep_alloc(struct eventpoll **pep)
	{		{
	struct eventpoll ep = kzalloc(sizeof(ep), GFP_KERNEL);		int error;
			struct user_struct *user;
			struct eventpoll *ep;

	if (!ep)		user = get_current_user();
	return -ENOMEM;		error = -EMFILE;
			if (unlikely(atomic_read(&user->epoll_devs) >=
			max_user_instances))
			goto free_uid;
			error = -ENOMEM;
			ep = kzalloc(sizeof(*ep), GFP_KERNEL);
			if (unlikely(!ep))
			goto free_uid;

	spin_lock_init(&ep->lock);		spin_lock_init(&ep->lock);
	mutex_init(&ep->mtx);		mutex_init(&ep->mtx);
	@@ -544,12 +597,17 @@ static int ep_alloc(struct eventpoll **pep)
	INIT_LIST_HEAD(&ep->rdllist);		INIT_LIST_HEAD(&ep->rdllist);
	ep->rbr = RB_ROOT;		ep->rbr = RB_ROOT;
	ep->ovflist = EP_UNACTIVE_PTR;		ep->ovflist = EP_UNACTIVE_PTR;
			ep->user = user;

	*pep = ep;		*pep = ep;

	DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_alloc() ep=%p\n",		DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_alloc() ep=%p\n",
	current, ep));		current, ep));
	return 0;		return 0;

			free_uid:
			free_uid(user);
			return error;
	}		}

	/*		/*
	@@ -703,9 +761,11 @@ static int ep_insert(struct eventpoll ep, struct epoll_event event,
	struct epitem *epi;		struct epitem *epi;
	struct ep_pqueue epq;		struct ep_pqueue epq;

	error = -ENOMEM;		if (unlikely(atomic_read(&ep->user->epoll_watches) >=
			max_user_watches))
			return -ENOSPC;
	if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))		if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
	goto error_return;		return -ENOMEM;

	/* Item initialization follow here ... */		/* Item initialization follow here ... */
	INIT_LIST_HEAD(&epi->rdllink);		INIT_LIST_HEAD(&epi->rdllink);
	@@ -735,6 +795,7 @@ static int ep_insert(struct eventpoll ep, struct epoll_event event,
	* install process. Namely an allocation for a wait queue failed due		* install process. Namely an allocation for a wait queue failed due
	* high memory pressure.		* high memory pressure.
	*/		*/
			error = -ENOMEM;
	if (epi->nwait < 0)		if (epi->nwait < 0)
	goto error_unregister;		goto error_unregister;

	@@ -765,6 +826,8 @@ static int ep_insert(struct eventpoll ep, struct epoll_event event,

	spin_unlock_irqrestore(&ep->lock, flags);		spin_unlock_irqrestore(&ep->lock, flags);

			atomic_inc(&ep->user->epoll_watches);

	/* We have to call this outside the lock */		/* We have to call this outside the lock */
	if (pwake)		if (pwake)
	ep_poll_safewake(&psw, &ep->poll_wait);		ep_poll_safewake(&psw, &ep->poll_wait);
	@@ -789,7 +852,7 @@ static int ep_insert(struct eventpoll ep, struct epoll_event event,
	spin_unlock_irqrestore(&ep->lock, flags);		spin_unlock_irqrestore(&ep->lock, flags);

	kmem_cache_free(epi_cache, epi);		kmem_cache_free(epi_cache, epi);
	error_return:
	return error;		return error;
	}		}

	@@ -1078,6 +1141,7 @@ asmlinkage long sys_epoll_create1(int flags)
	flags & O_CLOEXEC);		flags & O_CLOEXEC);
	if (fd < 0)		if (fd < 0)
	ep_free(ep);		ep_free(ep);
			atomic_inc(&ep->user->epoll_devs);

	error_return:		error_return:
	DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",		DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
	@@ -1299,7 +1363,12 @@ asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,

	static int __init eventpoll_init(void)		static int __init eventpoll_init(void)
	{		{
	mutex_init(&epmutex);		struct sysinfo si;

			si_meminfo(&si);
			max_user_instances = 128;
			max_user_watches = (((si.totalram - si.totalhigh) / 32) << PAGE_SHIFT) /
			EP_ITEM_COST;

	/* Initialize the structure used to perform safe poll wait head wake ups */		/* Initialize the structure used to perform safe poll wait head wake ups */
	ep_poll_safewake_init(&psw);		ep_poll_safewake_init(&psw);

include/linux/sched.h

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -630,6 +630,10 @@ struct user_struct {
	atomic_t inotify_watches; /* How many inotify watches does this user have? */		atomic_t inotify_watches; /* How many inotify watches does this user have? */
	atomic_t inotify_devs; /* How many inotify devs does this user have opened? */		atomic_t inotify_devs; /* How many inotify devs does this user have opened? */
	#endif		#endif
			#ifdef CONFIG_EPOLL
			atomic_t epoll_devs; /* The number of epoll descriptors currently open */
			atomic_t epoll_watches; /* The number of file descriptors currently watched */
			#endif
	#ifdef CONFIG_POSIX_MQUEUE		#ifdef CONFIG_POSIX_MQUEUE
	/* protected by mq_lock */		/* protected by mq_lock */
	unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */		unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */

kernel/sysctl.c

+10 −0

Original line number	Original line	Diff line number	Diff line
	@@ -176,6 +176,9 @@ extern struct ctl_table random_table[];
	#ifdef CONFIG_INOTIFY_USER		#ifdef CONFIG_INOTIFY_USER
	extern struct ctl_table inotify_table[];		extern struct ctl_table inotify_table[];
	#endif		#endif
			#ifdef CONFIG_EPOLL
			extern struct ctl_table epoll_table[];
			#endif

	#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT		#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
	int sysctl_legacy_va_layout;		int sysctl_legacy_va_layout;
	@@ -1325,6 +1328,13 @@ static struct ctl_table fs_table[] = {
	.child = inotify_table,		.child = inotify_table,
	},		},
	#endif		#endif
			#ifdef CONFIG_EPOLL
			{
			.procname = "epoll",
			.mode = 0555,
			.child = epoll_table,
			},
			#endif
	#endif		#endif
	{		{
	.ctl_name = KERN_SETUID_DUMPABLE,		.ctl_name = KERN_SETUID_DUMPABLE,