* [PATCH 1/2] mm/damon/dbgfs: Use '__GFP_NOWARN' for user-specified size buffer allocation
2021-11-10 14:57 [PATCH 0/2] DAMON fixes SeongJae Park
@ 2021-11-10 14:57 ` SeongJae Park
2021-11-10 14:57 ` [PATCH 2/2] mm/damon/dbgfs: Fix missed use of damon_dbgfs_lock SeongJae Park
2021-11-16 3:42 ` [PATCH 0/2] DAMON fixes Andrew Morton
2 siblings, 0 replies; 4+ messages in thread
From: SeongJae Park @ 2021-11-10 14:57 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, SeongJae Park
DAMON users can trigger below warning in '__alloc_pages()' by invoking
write() to some DAMON debugfs files with arbitrarily high count
argument, because DAMON debugfs interface allocates some buffers based
on the user-specified 'count'.
if (unlikely(order >= MAX_ORDER)) {
WARN_ON_ONCE(!(gfp & __GFP_NOWARN));
return NULL;
}
Because the DAMON debugfs interface code checks failure of the
'kmalloc()', this commit simply suppresses the warnings by adding
'__GFP_NOWARN' flag.
Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/dbgfs.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index eccc14b34901..8ce1311ac533 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -32,7 +32,7 @@ static char *user_input_str(const char __user *buf, size_t count, loff_t *ppos)
if (*ppos)
return ERR_PTR(-EINVAL);
- kbuf = kmalloc(count + 1, GFP_KERNEL);
+ kbuf = kmalloc(count + 1, GFP_KERNEL | __GFP_NOWARN);
if (!kbuf)
return ERR_PTR(-ENOMEM);
@@ -133,7 +133,7 @@ static ssize_t dbgfs_schemes_read(struct file *file, char __user *buf,
char *kbuf;
ssize_t len;
- kbuf = kmalloc(count, GFP_KERNEL);
+ kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
if (!kbuf)
return -ENOMEM;
@@ -452,7 +452,7 @@ static ssize_t dbgfs_init_regions_read(struct file *file, char __user *buf,
char *kbuf;
ssize_t len;
- kbuf = kmalloc(count, GFP_KERNEL);
+ kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
if (!kbuf)
return -ENOMEM;
@@ -578,7 +578,7 @@ static ssize_t dbgfs_kdamond_pid_read(struct file *file,
char *kbuf;
ssize_t len;
- kbuf = kmalloc(count, GFP_KERNEL);
+ kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
if (!kbuf)
return -ENOMEM;
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] mm/damon/dbgfs: Fix missed use of damon_dbgfs_lock
2021-11-10 14:57 [PATCH 0/2] DAMON fixes SeongJae Park
2021-11-10 14:57 ` [PATCH 1/2] mm/damon/dbgfs: Use '__GFP_NOWARN' for user-specified size buffer allocation SeongJae Park
@ 2021-11-10 14:57 ` SeongJae Park
2021-11-16 3:42 ` [PATCH 0/2] DAMON fixes Andrew Morton
2 siblings, 0 replies; 4+ messages in thread
From: SeongJae Park @ 2021-11-10 14:57 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, SeongJae Park
DAMON debugfs is supposed to protect dbgfs_ctxs, dbgfs_nr_ctxs, and
dbgfs_dirs using damon_dbgfs_lock. However, some of the code is
accessing the variables without the protection. This commit fixes it by
protecting all such accesses.
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/dbgfs.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 8ce1311ac533..9b520bb4a3e7 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -877,12 +877,14 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
return -EINVAL;
}
+ mutex_lock(&damon_dbgfs_lock);
if (!strncmp(kbuf, "on", count)) {
int i;
for (i = 0; i < dbgfs_nr_ctxs; i++) {
if (damon_targets_empty(dbgfs_ctxs[i])) {
kfree(kbuf);
+ mutex_unlock(&damon_dbgfs_lock);
return -EINVAL;
}
}
@@ -892,6 +894,7 @@ static ssize_t dbgfs_monitor_on_write(struct file *file,
} else {
ret = -EINVAL;
}
+ mutex_unlock(&damon_dbgfs_lock);
if (!ret)
ret = count;
@@ -944,15 +947,16 @@ static int __init __damon_dbgfs_init(void)
static int __init damon_dbgfs_init(void)
{
- int rc;
+ int rc = -ENOMEM;
+ mutex_lock(&damon_dbgfs_lock);
dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL);
if (!dbgfs_ctxs)
- return -ENOMEM;
+ goto out;
dbgfs_ctxs[0] = dbgfs_new_ctx();
if (!dbgfs_ctxs[0]) {
kfree(dbgfs_ctxs);
- return -ENOMEM;
+ goto out;
}
dbgfs_nr_ctxs = 1;
@@ -963,6 +967,8 @@ static int __init damon_dbgfs_init(void)
pr_err("%s: dbgfs init failed\n", __func__);
}
+out:
+ mutex_unlock(&damon_dbgfs_lock);
return rc;
}
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread