[v6,08/16] memcg: enable accounting for pollfd and select bits arrays

Commit Message

Vasily Averin July 26, 2021, 7 p.m. UTC

User can call select/poll system calls with a large number of assigned
file descriptors and force kernel to allocate up to several pages of memory
till end of these sleeping system calls. We have here long-living
unaccounted per-task allocations.

It makes sense to account for these allocations to restrict the host's
memory consumption from inside the memcg-limited container.

Signed-off-by: Vasily Averin <[e-mail]>
---
 fs/select.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/select.c b/fs/select.c
index 945896d..e83e563 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -655,7 +655,7 @@  int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
 			goto out_nofds;
 
 		alloc_size = 6 * size;
-		bits = kvmalloc(alloc_size, GFP_KERNEL);
+		bits = kvmalloc(alloc_size, GFP_KERNEL_ACCOUNT);
 		if (!bits)
 			goto out_nofds;
 	}
@@ -1000,7 +1000,7 @@  static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 
 		len = min(todo, POLLFD_PER_PAGE);
 		walk = walk->next = kmalloc(struct_size(walk, entries, len),
-					    GFP_KERNEL);
+					    GFP_KERNEL_ACCOUNT);
 		if (!walk) {
 			err = -ENOMEM;
 			goto out_fds;