Vivek Goyal <vgoyal@xxxxxxxxxx> writes: > On Tue, Mar 16, 2021 at 05:02:34PM +0000, Luis Henriques wrote: >> When accidentally passing twice the same tag to qemu, kmemleak ended up >> reporting a memory leak in virtiofs. Also, looking at the log I saw the >> following error (that's when I realised the duplicated tag): >> >> virtiofs: probe of virtio5 failed with error -17 >> >> Here's the kmemleak log for reference: >> >> unreferenced object 0xffff888103d47800 (size 1024): >> comm "systemd-udevd", pid 118, jiffies 4294893780 (age 18.340s) >> hex dump (first 32 bytes): >> 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... >> ff ff ff ff ff ff ff ff 80 90 02 a0 ff ff ff ff ................ >> backtrace: >> [<000000000ebb87c1>] virtio_fs_probe+0x171/0x7ae [virtiofs] >> [<00000000f8aca419>] virtio_dev_probe+0x15f/0x210 >> [<000000004d6baf3c>] really_probe+0xea/0x430 >> [<00000000a6ceeac8>] device_driver_attach+0xa8/0xb0 >> [<00000000196f47a7>] __driver_attach+0x98/0x140 >> [<000000000b20601d>] bus_for_each_dev+0x7b/0xc0 >> [<00000000399c7b7f>] bus_add_driver+0x11b/0x1f0 >> [<0000000032b09ba7>] driver_register+0x8f/0xe0 >> [<00000000cdd55998>] 0xffffffffa002c013 >> [<000000000ea196a2>] do_one_initcall+0x64/0x2e0 >> [<0000000008f727ce>] do_init_module+0x5c/0x260 >> [<000000003cdedab6>] __do_sys_finit_module+0xb5/0x120 >> [<00000000ad2f48c6>] do_syscall_64+0x33/0x40 >> [<00000000809526b5>] entry_SYSCALL_64_after_hwframe+0x44/0xae >> >> Cc: stable@xxxxxxxxxxxxxxx >> Signed-off-by: Luis Henriques <lhenriques@xxxxxxx> > > Hi Luis, > > Thanks for the report and the fix. So looks like leak is happening > because we are not doing kfree(fs->vqs) in error path. Yep! >> --- >> fs/fuse/virtio_fs.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c >> index 8868ac31a3c0..4e6ef9f24e84 100644 >> --- a/fs/fuse/virtio_fs.c >> +++ b/fs/fuse/virtio_fs.c >> @@ -899,7 +899,7 @@ static int virtio_fs_probe(struct virtio_device *vdev) >> >> out: >> vdev->priv = NULL; >> - kfree(fs); >> + virtio_fs_put(fs); > > [ CC virtio-fs list ] Oops, forgot to include it. Maybe it should be added to the MAINTAINERS file (although IIRC it's not an open list). > fs object is not fully formed. So calling virtio_fs_put() is little odd. > I will expect it to be called if somebody takes a reference using _get() > or in the final virtio_fs_remove() when creation reference should go > away. > > How about open coding it and free fs->vqs explicitly. Something like > as follows. Ok, I'll send v2 later (I'm currently away from my devel workstation). To be honest, my initial version was doing exactly what you're suggesting. I decided to change to virtio_fs_put() because the refcount was already initialised early in the function. Bad decision. Cheers, -- Luis > > @@ -896,7 +896,7 @@ static int virtio_fs_probe(struct virtio > out_vqs: > vdev->config->reset(vdev); > virtio_fs_cleanup_vqs(vdev, fs); > - > + kfree(fs->vqs); > out: > vdev->priv = NULL; > kfree(fs); > > Thanks > Vivek >
