From: Waiman Long <longman@redhat.com>
To: Jan Kara <jack@suse.cz>, Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Luca BRUNO <lucab@redhat.com>, Waiman Long <longman@redhat.com>
Subject: [PATCH] inotify: Increase default inotify.max_user_watches limit to 1048576
Date: Mon, 26 Oct 2020 16:44:18 -0400 [thread overview]
Message-ID: <20201026204418.23197-1-longman@redhat.com> (raw)
The default value of inotify.max_user_watches sysctl parameter was set
to 8192 since the introduction of the inotify feature in 2005 by
commit 0eeca28300df ("[PATCH] inotify"). Today this value is just too
small for many modern usage. As a result, users have to explicitly set
it to a larger value to make it work.
After some searching around the web, these are the
inotify.max_user_watches values used by some projects:
- vscode: 524288
- dropbox support: 100000
- users on stackexchange: 12228
- lsyncd user: 2000000
- code42 support: 1048576
- monodevelop: 16384
- tectonic: 524288
- openshift origin: 65536
Each watch point adds an inotify_inode_mark structure to an inode to be
watched. Modeled after the epoll.max_user_watches behavior to adjust the
default value according to the amount of addressable memory available,
make inotify.max_user_watches behave in a similar way to make it use
no more than 1% of addressable memory within the range [8192, 1048576].
For 64-bit archs, inotify_inode_mark should have a size of 80 bytes. That
means a system with 8GB or more memory will have the maximum value of
1048576 for inotify.max_user_watches. This default should be big enough
for most of the use cases.
Signed-off-by: Waiman Long <longman@redhat.com>
---
fs/notify/inotify/inotify_user.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 186722ba3894..2da8b7a84b12 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -801,6 +801,18 @@ SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
*/
static int __init inotify_user_setup(void)
{
+ unsigned int watches_max;
+ struct sysinfo si;
+
+ si_meminfo(&si);
+ /*
+ * Allow up to 1% of addressible memory to be allocated for inotify
+ * watches (per user) limited to the range [8192, 1048576].
+ */
+ watches_max = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
+ sizeof(struct inotify_inode_mark);
+ watches_max = min(1048576U, max(watches_max, 8192U));
+
BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
@@ -827,7 +839,7 @@ static int __init inotify_user_setup(void)
inotify_max_queued_events = 16384;
init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
- init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192;
+ init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = watches_max;
return 0;
}
--
2.18.1
next reply other threads:[~2020-10-26 20:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 20:44 Waiman Long [this message]
2020-10-27 8:19 ` [PATCH] inotify: Increase default inotify.max_user_watches limit to 1048576 Amir Goldstein
2020-10-27 16:00 ` Jan Kara
2020-10-29 14:25 ` Waiman Long
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