From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:55354 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728471AbeLJRNi (ORCPT ); Mon, 10 Dec 2018 12:13:38 -0500 From: Vivek Goyal To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: vgoyal@redhat.com, miklos@szeredi.hu, stefanha@redhat.com, dgilbert@redhat.com, sweil@redhat.com, swhiteho@redhat.com Subject: [PATCH 41/52] fuse: Reschedule dax free work if too many EAGAIN attempts Date: Mon, 10 Dec 2018 12:13:07 -0500 Message-Id: <20181210171318.16998-42-vgoyal@redhat.com> In-Reply-To: <20181210171318.16998-1-vgoyal@redhat.com> References: <20181210171318.16998-1-vgoyal@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: fuse_dax_free_memory() can be very cpu intensive in corner cases. For example, if one inode has consumed all the memory and a setupmapping request is pending, that means inode lock is held by request and worker thread will not get lock for a while. And given there is only one inode consuming all the dax ranges, all the attempts to acquire lock will fail. So if there are too many inode lock failures (-EAGAIN), reschedule the worker with a 10ms delay. Signed-off-by: Vivek Goyal --- fs/fuse/file.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index dbe3410a94d7..709747458335 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -3909,7 +3909,7 @@ int fuse_dax_free_one_mapping(struct fuse_conn *fc, struct inode *inode, int fuse_dax_free_memory(struct fuse_conn *fc, unsigned long nr_to_free) { struct fuse_dax_mapping *dmap, *pos, *temp; - int ret, nr_freed = 0; + int ret, nr_freed = 0, nr_eagain = 0; u64 dmap_start = 0, window_offset = 0; struct inode *inode = NULL; @@ -3918,6 +3918,12 @@ int fuse_dax_free_memory(struct fuse_conn *fc, unsigned long nr_to_free) if (nr_freed >= nr_to_free) break; + if (nr_eagain > 20) { + queue_delayed_work(system_long_wq, &fc->dax_free_work, + msecs_to_jiffies(10)); + return 0; + } + dmap = NULL; spin_lock(&fc->lock); @@ -3955,8 +3961,10 @@ int fuse_dax_free_memory(struct fuse_conn *fc, unsigned long nr_to_free) } /* Could not get inode lock. Try next element */ - if (ret == -EAGAIN) + if (ret == -EAGAIN) { + nr_eagain++; continue; + } nr_freed++; } return 0; -- 2.13.6