This patch limits the size of total memory that can be requested in a single allocation from the system heap. This would prevent a buggy/malicious client from depleting system memory by requesting for an extremely large allocation which might destabilize the system.
The limit is set to half the size of the device's total RAM which is the same as what was set by the deprecated ION system heap.
Signed-off-by: Hridya Valsaraju hridya@google.com --- drivers/dma-buf/heaps/system_heap.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index b7fbce66bcc0..099f5a8304b4 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -371,6 +371,12 @@ static struct dma_buf *system_heap_do_allocate(struct dma_heap *heap, struct page *page, *tmp_page; int i, ret = -ENOMEM;
+ if (len / PAGE_SIZE > totalram_pages() / 2) { + pr_err("pid %d requested too large an allocation(size %lu) from system heap\n", + current->pid, len); + return ERR_PTR(ret); + } + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); if (!buffer) return ERR_PTR(-ENOMEM);
On Thu, Jul 22, 2021 at 12:07 PM Hridya Valsaraju hridya@google.com wrote:
Seems sane to me, unless folks have better suggestions for allocation limits.
Reviewed-by: John Stultz john.stultz@linaro.org
thanks -john
On Mon, Aug 2, 2021 at 7:18 PM John Stultz john.stultz@linaro.org wrote:
Thank you for taking a look John!
Regards, Hridya
thanks -john
Hi Hridya,
Apologies for the delay in responding.
On Wed, 4 Aug 2021 at 03:09, Hridya Valsaraju hridya@google.com wrote:
Looks good to me; I will apply it to drm-misc today.
Best, Sumit.
On Tue, Aug 10, 2021 at 01:54:41PM +0530, Sumit Semwal wrote:
Please don't, this doesn't really solve anything: - it's easy to bypass, just allocate more buffers to get over the limit - resource limit plan is cgroups, not hand-rolled limits in every allocator - the ttm "max half of system memory" is for pinned memory, to work around locking inversion issues between dma_resv_lock and core mm shrinkers. It does not actually impose an overall allocation limit, you can allocate ttm bo until your entire memory (and swap) are full. Christian König has merged a patch set to lift this by reworking the shrinker interaction, but it had to be reverted again because of some fallout I can't remember offhand. dma_resv_lock vs shrinkers is very tricky.
So if you want resource limits then you really want cgroups here.
Cheers, Daniel
On Tue, Aug 10, 2021 at 1:40 AM Daniel Vetter daniel@ffwll.ch wrote:
Thanks Daniel and Sumit, that makes sense. Once the GPU memory accounting cgroups are ready, we should be able to set the limit using the same.
Regards, Hridya
Hi Hridya,
Apologies for the delay in responding;
On Wed, 4 Aug 2021 at 03:09, Hridya Valsaraju hridya@google.com wrote:
Looks good to me; I will apply it to drm-misc today.
Best, Sumit.
linaro-mm-sig@lists.linaro.org
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Daniel Vetter -
Hridya Valsaraju -
John Stultz -
Sumit Semwal