The patch titled
Subject: fork: protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs
has been added to the -mm tree. Its filename is
fork-protect-architectures-where-thread_size-=-page_size-against-fork-bombs.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Glauber Costa <glommer@xxxxxxxxxxxxx>
Subject: fork: protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs
Because those architectures will draw their stacks directly from the page
allocator, rather than the slab cache, we can directly pass __GFP_KMEMCG
flag, and issue the corresponding free_pages.
This code path is taken when the architecture doesn't define
CONFIG_ARCH_THREAD_INFO_ALLOCATOR (only ia64 seems to), and has
THREAD_SIZE >= PAGE_SIZE. Luckily, most - if not all - of the remaining
architectures fall in this category.
This will guarantee that every stack page is accounted to the memcg the
process currently lives on, and will have the allocations to fail if they
go over limit.
For the time being, I am defining a new variant of THREADINFO_GFP, not to
mess with the other path. Once the slab is also tracked by memcg, we can
get rid of that flag.
Tested to successfully protect against :(){ :|:& };:
Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxxx>
Acked-by: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: JoonSoo Kim <js1304@xxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/thread_info.h | 2 ++
kernel/fork.c | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff -puN include/linux/thread_info.h~fork-protect-architectures-where-thread_size-=-page_size-against-fork-bombs include/linux/thread_info.h
--- a/include/linux/thread_info.h~fork-protect-architectures-where-thread_size-=-page_size-against-fork-bombs
+++ a/include/linux/thread_info.h
@@ -61,6 +61,8 @@ extern long do_no_restart_syscall(struct
# define THREADINFO_GFP (GFP_KERNEL | __GFP_NOTRACK)
#endif
+#define THREADINFO_GFP_ACCOUNTED (THREADINFO_GFP | __GFP_KMEMCG)
+
/*
* flag set/clear/test wrappers
* - pass TIF_xxxx constants to these functions
diff -puN kernel/fork.c~fork-protect-architectures-where-thread_size-=-page_size-against-fork-bombs kernel/fork.c
--- a/kernel/fork.c~fork-protect-architectures-where-thread_size-=-page_size-against-fork-bombs
+++ a/kernel/fork.c
@@ -146,7 +146,7 @@ void __weak arch_release_thread_info(str
static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
int node)
{
- struct page *page = alloc_pages_node(node, THREADINFO_GFP,
+ struct page *page = alloc_pages_node(node, THREADINFO_GFP_ACCOUNTED,
THREAD_SIZE_ORDER);
return page ? page_address(page) : NULL;
@@ -154,7 +154,7 @@ static struct thread_info *alloc_thread_
static inline void free_thread_info(struct thread_info *ti)
{
- free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
+ free_memcg_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER);
}
# else
static struct kmem_cache *thread_info_cache;
_
Patches currently in -mm which might be from glommer@xxxxxxxxxxxxx are
linux-next.patch
memcg-make-it-possible-to-use-the-stock-for-more-than-one-page.patch
memcg-reclaim-when-more-than-one-page-needed.patch
memcg-change-defines-to-an-enum.patch
memcg-kmem-accounting-basic-infrastructure.patch
mm-add-a-__gfp_kmemcg-flag.patch
memcg-kmem-controller-infrastructure.patch
mm-allocate-kernel-pages-to-the-right-memcg.patch
res_counter-return-amount-of-charges-after-res_counter_uncharge.patch
memcg-kmem-accounting-lifecycle-management.patch
memcg-use-static-branches-when-code-not-in-use.patch
memcg-allow-a-memcg-with-kmem-charges-to-be-destructed.patch
memcg-execute-the-whole-memcg-freeing-in-free_worker.patch
fork-protect-architectures-where-thread_size-=-page_size-against-fork-bombs.patch
memcg-add-documentation-about-the-kmem-controller.patch
slab-slub-struct-memcg_params.patch
slab-annotate-on-slab-caches-nodelist-locks.patch
slab-slub-consider-a-memcg-parameter-in-kmem_create_cache.patch
memcg-allocate-memory-for-memcg-caches-whenever-a-new-memcg-appears.patch
memcg-infrastructure-to-match-an-allocation-to-the-right-cache.patch
memcg-skip-memcg-kmem-allocations-in-specified-code-regions.patch
slb-always-get-the-cache-from-its-page-in-kmem_cache_free.patch
slb-allocate-objects-from-memcg-cache.patch
memcg-destroy-memcg-caches.patch
memcg-slb-track-all-the-memcg-children-of-a-kmem_cache.patch
memcg-slb-shrink-dead-caches.patch
memcg-aggregate-memcg-cache-values-in-slabinfo.patch
slab-propagate-tunable-values.patch
slub-slub-specific-propagation-changes.patch
kmem-add-slab-specific-documentation-about-the-kmem-controller.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
