lkml.org 
[lkml]   [2022]   [Mar]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK
Date
Since page migration / swapping is not supported yet, MFD_INACCESSIBLE
memory behave like longterm pinned pages and thus should be accounted to
mm->pinned_vm and be restricted by RLIMIT_MEMLOCK.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
mm/shmem.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 7b43e274c9a2..ae46fb96494b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -915,14 +915,17 @@ static void notify_fallocate(struct inode *inode, pgoff_t start, pgoff_t end)
static void notify_invalidate_page(struct inode *inode, struct folio *folio,
pgoff_t start, pgoff_t end)
{
-#ifdef CONFIG_MEMFILE_NOTIFIER
struct shmem_inode_info *info = SHMEM_I(inode);

+#ifdef CONFIG_MEMFILE_NOTIFIER
start = max(start, folio->index);
end = min(end, folio->index + folio_nr_pages(folio));

memfile_notifier_invalidate(&info->memfile_notifiers, start, end);
#endif
+
+ if (info->xflags & SHM_F_INACCESSIBLE)
+ atomic64_sub(end - start, &current->mm->pinned_vm);
}

/*
@@ -2680,6 +2683,20 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
return offset;
}

+static bool memlock_limited(unsigned long npages)
+{
+ unsigned long lock_limit;
+ unsigned long pinned;
+
+ lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+ pinned = atomic64_add_return(npages, &current->mm->pinned_vm);
+ if (pinned > lock_limit && !capable(CAP_IPC_LOCK)) {
+ atomic64_sub(npages, &current->mm->pinned_vm);
+ return true;
+ }
+ return false;
+}
+
static long shmem_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
@@ -2753,6 +2770,12 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
goto out;
}

+ if ((info->xflags & SHM_F_INACCESSIBLE) &&
+ memlock_limited(end - start)) {
+ error = -ENOMEM;
+ goto out;
+ }
+
shmem_falloc.waitq = NULL;
shmem_falloc.start = start;
shmem_falloc.next = start;
--
2.17.1
\
 
 \ /
  Last update: 2022-03-10 15:11    [W:1.039 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site