[PATCH AUTOSEL 5.1 131/141] memcg, fsnotify: no oom-kill for remote memcg charging

[PATCH AUTOSEL 5.1 131/141] memcg, fsnotify: no oom-kill for remote memcg charging

[Sasha Levin]

From: Shakeel Butt <shakeelb@google.com>

[ Upstream commit ec165450968b26298bd1c373de37b0ab6d826b33 ]

Commit d46eb14b735b ("fs: fsnotify: account fsnotify metadata to
kmemcg") added remote memcg charging for fanotify and inotify event
objects.  The aim was to charge the memory to the listener who is
interested in the events but without triggering the OOM killer.
Otherwise there would be security concerns for the listener.

At the time, oom-kill trigger was not in the charging path.  A parallel
work added the oom-kill back to charging path i.e.  commit 29ef680ae7c2
("memcg, oom: move out_of_memory back to the charge path").  So to not
trigger oom-killer in the remote memcg, explicitly add
__GFP_RETRY_MAYFAIL to the fanotigy and inotify event allocations.

Link: http://lkml.kernel.org/r/20190514212259.156585-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/notify/fanotify/fanotify.c        | 5 ++++-
 fs/notify/inotify/inotify_fsnotify.c | 8 ++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 8c286f8228e5..d5db722ac272 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -288,10 +288,13 @@ struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
 	/*
 	 * For queues with unlimited length lost events are not expected and
 	 * can possibly have security implications. Avoid losing events when
-	 * memory is short.
+	 * memory is short. For the limited size queues, avoid OOM killer in the
+	 * target monitoring memcg as it may have security repercussion.
 	 */
 	if (group->max_events == UINT_MAX)
 		gfp |= __GFP_NOFAIL;
+	else
+		gfp |= __GFP_RETRY_MAYFAIL;
 
 	/* Whoever is interested in the event, pays for the allocation. */
 	memalloc_use_memcg(group->memcg);
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index ff30abd6a49b..ca1a9dfff0b5 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -99,9 +99,13 @@ int inotify_handle_event(struct fsnotify_group *group,
 	i_mark = container_of(inode_mark, struct inotify_inode_mark,
 			      fsn_mark);
 
-	/* Whoever is interested in the event, pays for the allocation. */
+	/*
+	 * Whoever is interested in the event, pays for the allocation. Do not
+	 * trigger OOM killer in the target monitoring memcg as it may have
+	 * security repercussion.
+	 */
 	memalloc_use_memcg(group->memcg);
-	event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT);
+	event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
 	memalloc_unuse_memcg();
 
 	if (unlikely(!event)) {
-- 
2.20.1

[PATCH AUTOSEL 5.1 133/141] proc: use down_read_killable mmap_sem for /proc/pid/smaps_rollup

[Sasha Levin]

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ Upstream commit a26a97815548574213fd37f29b4b78ccc6d9ed20 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Link: http://lkml.kernel.org/r/156007493429.3335.14666825072272692455.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/proc/task_mmu.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 95ca1fe7283c..c5b1b6db9a70 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -828,7 +828,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 
 	memset(&mss, 0, sizeof(mss));
 
-	down_read(&mm->mmap_sem);
+	ret = down_read_killable(&mm->mmap_sem);
+	if (ret)
+		goto out_put_mm;
+
 	hold_task_mempolicy(priv);
 
 	for (vma = priv->mm->mmap; vma; vma = vma->vm_next) {
@@ -845,8 +848,9 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 
 	release_task_mempolicy(priv);
 	up_read(&mm->mmap_sem);
-	mmput(mm);
 
+out_put_mm:
+	mmput(mm);
 out_put_task:
 	put_task_struct(priv->task);
 	priv->task = NULL;
-- 
2.20.1

[PATCH AUTOSEL 5.1 134/141] proc: use down_read_killable mmap_sem for /proc/pid/pagemap

[Sasha Levin]

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ Upstream commit ad80b932c57d85fd6377f97f359b025baf179a87 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Link: http://lkml.kernel.org/r/156007493638.3335.4872164955523928492.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/proc/task_mmu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index c5b1b6db9a70..8b1376c42647 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1542,7 +1542,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 		/* overflow ? */
 		if (end < start_vaddr || end > end_vaddr)
 			end = end_vaddr;
-		down_read(&mm->mmap_sem);
+		ret = down_read_killable(&mm->mmap_sem);
+		if (ret)
+			goto out_free;
 		ret = walk_page_range(start_vaddr, end, &pagemap_walk);
 		up_read(&mm->mmap_sem);
 		start_vaddr = end;
-- 
2.20.1

[PATCH AUTOSEL 5.1 135/141] proc: use down_read_killable mmap_sem for /proc/pid/clear_refs

[Sasha Levin]

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Replace the only unkillable mmap_sem lock in clear_refs_write().

Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/proc/task_mmu.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8b1376c42647..d544ab2e4210 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1136,7 +1136,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 			goto out_mm;
 		}
 
-		down_read(&mm->mmap_sem);
+		if (down_read_killable(&mm->mmap_sem)) {
+			count = -EINTR;
+			goto out_mm;
+		}
 		tlb_gather_mmu(&tlb, mm, 0, -1);
 		if (type == CLEAR_REFS_SOFT_DIRTY) {
 			for (vma = mm->mmap; vma; vma = vma->vm_next) {
-- 
2.20.1

[PATCH AUTOSEL 5.1 136/141] proc: use down_read_killable mmap_sem for /proc/pid/map_files

[Sasha Levin]

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ Upstream commit cd9e2bb8271c971d9f37c722be2616c7f8ba0664 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

It seems ->d_revalidate() could return any error (except ECHILD) to abort
validation and pass error as result of lookup sequence.

[akpm@linux-foundation.org: fix proc_map_files_lookup() return value, per Andrei]
Link: http://lkml.kernel.org/r/156007493995.3335.9595044802115356911.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/proc/base.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 0c9bef89ac43..0325906aec27 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1967,9 +1967,12 @@ static int map_files_d_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out;
 
 	if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
-		down_read(&mm->mmap_sem);
-		exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
-		up_read(&mm->mmap_sem);
+		status = down_read_killable(&mm->mmap_sem);
+		if (!status) {
+			exact_vma_exists = !!find_exact_vma(mm, vm_start,
+							    vm_end);
+			up_read(&mm->mmap_sem);
+		}
 	}
 
 	mmput(mm);
@@ -2015,8 +2018,11 @@ static int map_files_get_link(struct dentry *dentry, struct path *path)
 	if (rc)
 		goto out_mmput;
 
+	rc = down_read_killable(&mm->mmap_sem);
+	if (rc)
+		goto out_mmput;
+
 	rc = -ENOENT;
-	down_read(&mm->mmap_sem);
 	vma = find_exact_vma(mm, vm_start, vm_end);
 	if (vma && vma->vm_file) {
 		*path = vma->vm_file->f_path;
@@ -2112,7 +2118,11 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 	if (!mm)
 		goto out_put_task;
 
-	down_read(&mm->mmap_sem);
+	result = ERR_PTR(-EINTR);
+	if (down_read_killable(&mm->mmap_sem))
+		goto out_put_mm;
+
+	result = ERR_PTR(-ENOENT);
 	vma = find_exact_vma(mm, vm_start, vm_end);
 	if (!vma)
 		goto out_no_vma;
@@ -2123,6 +2133,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 
 out_no_vma:
 	up_read(&mm->mmap_sem);
+out_put_mm:
 	mmput(mm);
 out_put_task:
 	put_task_struct(task);
@@ -2165,7 +2176,12 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 	mm = get_task_mm(task);
 	if (!mm)
 		goto out_put_task;
-	down_read(&mm->mmap_sem);
+
+	ret = down_read_killable(&mm->mmap_sem);
+	if (ret) {
+		mmput(mm);
+		goto out_put_task;
+	}
 
 	nr_files = 0;
 
-- 
2.20.1

[PATCH AUTOSEL 5.1 138/141] proc: use down_read_killable mmap_sem for /proc/pid/maps

[Sasha Levin]

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ Upstream commit 8a713e7df3352b8d9392476e9cf29e4e185dac32 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

This function is also used for /proc/pid/smaps.

Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/proc/task_mmu.c   | 6 +++++-
 fs/proc/task_nommu.c | 6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index d544ab2e4210..d416657bfbb7 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -166,7 +166,11 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 	if (!mm || !mmget_not_zero(mm))
 		return NULL;
 
-	down_read(&mm->mmap_sem);
+	if (down_read_killable(&mm->mmap_sem)) {
+		mmput(mm);
+		return ERR_PTR(-EINTR);
+	}
+
 	hold_task_mempolicy(priv);
 	priv->tail_vma = get_gate_vma(mm);
 
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 36bf0f2e102e..7907e6419e57 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -211,7 +211,11 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 	if (!mm || !mmget_not_zero(mm))
 		return NULL;
 
-	down_read(&mm->mmap_sem);
+	if (down_read_killable(&mm->mmap_sem)) {
+		mmput(mm);
+		return ERR_PTR(-EINTR);
+	}
+
 	/* start from the Nth VMA */
 	for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
 		if (n-- == 0)
-- 
2.20.1