The patch titled Subject: proc/sysctl: don't return ENOMEM on lookup when a table is unregistering has been added to the -mm tree. Its filename is proc-sysctl-dont-return-enomem-on-lookup-when-a-table-is-unregistering.patch

This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/proc-sysctl-dont-return-enomem-on-l... and later at http://ozlabs.org/~akpm/mmotm/broken-out/proc-sysctl-dont-return-enomem-on-l...

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------------------------------------------------------ From: Ivan Delalande colona@arista.com Subject: proc/sysctl: don't return ENOMEM on lookup when a table is unregistering

proc_sys_lookup can fail with ENOMEM instead of ENOENT when the corresponding sysctl table is being unregistered. In our case we see this upon opening /proc/sys/net/*/conf files while network interfaces are being deleted, which confuses our configuration daemon.

The problem was successfully reproduced and this fix tested on v4.9.122 and v4.20-rc6.

Link: http://lkml.kernel.org/r/20181213232052.GA1513@visor Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Signed-off-by: Ivan Delalande colona@arista.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Luis Chamberlain mcgrof@kernel.org Cc: Kees Cook keescook@chromium.org Cc: Al Viro viro@zeniv.linux.org.uk Cc: "Eric W. Biederman" ebiederm@xmission.com Cc: Alexey Dobriyan adobriyan@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

--- a/fs/proc/proc_sysctl.c~proc-sysctl-dont-return-enomem-on-lookup-when-a-table-is-unregistering +++ a/fs/proc/proc_sysctl.c @@ -464,7 +464,7 @@ static struct inode *proc_sys_make_inode

inode = new_inode(sb); if (!inode) - goto out; + return ERR_PTR(-ENOMEM);

inode->i_ino = get_next_ino();

@@ -474,7 +474,7 @@ static struct inode *proc_sys_make_inode if (unlikely(head->unregistering)) { spin_unlock(&sysctl_lock); iput(inode); - inode = NULL; + inode = ERR_PTR(-ENOENT); goto out; } ei->sysctl = head; @@ -549,10 +549,11 @@ static struct dentry *proc_sys_lookup(st goto out; }

- err = ERR_PTR(-ENOMEM); inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); - if (!inode) + if (IS_ERR(inode)) { + err = ERR_CAST(inode); goto out; + }

d_set_d_op(dentry, &proc_sys_dentry_operations); err = d_splice_alias(inode, dentry); @@ -685,7 +686,7 @@ static bool proc_sys_fill_cache(struct f if (d_in_lookup(child)) { struct dentry *res; inode = proc_sys_make_inode(dir->d_sb, head, table); - if (!inode) { + if (IS_ERR(inode)) { d_lookup_done(child); dput(child); return false; _

Patches currently in -mm which might be from colona@arista.com are

proc-sysctl-dont-return-enomem-on-lookup-when-a-table-is-unregistering.patch