From d1698dc8a590119014dd2f893b7cefa3b301739e Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 2 Jan 2018 10:02:19 +0000 Subject: fscache: Fix the default for fscache_maybe_release_page() commit 98801506552593c9b8ac11021b0cdad12cab4f6b upstream. Fix the default for fscache_maybe_release_page() for when the cookie isn't valid or the page isn't cached. It mustn't return false as that indicates the page cannot yet be freed. The problem with the default is that if, say, there's no cache, but a network filesystem's pages are using up almost all the available memory, a system can OOM because the filesystem ->releasepage() op will not allow them to be released as fscache_maybe_release_page() incorrectly prevents it. This can be tested by writing a sequence of 512MiB files to an AFS mount. It does not affect NFS or CIFS because both of those wrap the call in a check of PG_fscache and it shouldn't bother Ceph as that only has PG_private set whilst writeback is in progress. This might be an issue for 9P, however. Note that the pages aren't entirely stuck. Removing a file or unmounting will clear things because that uses ->invalidatepage() instead. Fixes: 201a15428bd5 ("FS-Cache: Handle pages pending storage that get evicted under OOM conditions") Reported-by: Marc Dionne Signed-off-by: David Howells Reviewed-by: Jeff Layton Acked-by: Al Viro Tested-by: Marc Dionne Signed-off-by: Greg Kroah-Hartman --- include/linux/fscache.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/fscache.h b/include/linux/fscache.h index 115bb81912cc..94a8aae8f9e2 100644 --- a/include/linux/fscache.h +++ b/include/linux/fscache.h @@ -764,7 +764,7 @@ bool fscache_maybe_release_page(struct fscache_cookie *cookie, { if (fscache_cookie_valid(cookie) && PageFsCache(page)) return __fscache_maybe_release_page(cookie, page, gfp); - return false; + return true; } /** -- cgit v1.2.3 From 58330ec2fecd1c3a6b8759b292f32f82dfd058ba Mon Sep 17 00:00:00 2001 From: Thiago Rafael Becker Date: Thu, 14 Dec 2017 15:33:12 -0800 Subject: kernel: make groups_sort calling a responsibility group_info allocators commit bdcf0a423ea1c40bbb40e7ee483b50fc8aa3d758 upstream. In testing, we found that nfsd threads may call set_groups in parallel for the same entry cached in auth.unix.gid, racing in the call of groups_sort, corrupting the groups for that entry and leading to permission denials for the client. This patch: - Make groups_sort globally visible. - Move the call to groups_sort to the modifiers of group_info - Remove the call to groups_sort from set_groups Link: http://lkml.kernel.org/r/20171211151420.18655-1-thiago.becker@gmail.com Signed-off-by: Thiago Rafael Becker Reviewed-by: Matthew Wilcox Reviewed-by: NeilBrown Acked-by: "J. Bruce Fields" Cc: Al Viro Cc: Martin Schwidefsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/cred.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/cred.h b/include/linux/cred.h index 257db64562e5..9e120c92551b 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -87,6 +87,7 @@ extern int set_current_groups(struct group_info *); extern void set_groups(struct cred *, struct group_info *); extern int groups_search(const struct group_info *, kgid_t); extern bool may_setgroups(void); +extern void groups_sort(struct group_info *); /* access the groups "array" with this macro */ #define GROUP_AT(gi, i) \ -- cgit v1.2.3