2021-07-27 05:35:54

by Vasily Averin

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Subject: [PATCH v7 02/10] memcg: enable accounting for pollfd and select bits arrays

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 <[email protected]>
---
fs/select.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

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;
--
1.8.3.1