Linux: How does opengl handle memory management ？

Tool/software: Linux

Our application runs on ram which has only 512 MB, So memory management is important.

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We found that when we create a opengl tex with glgentexture, the memory does not grow,

and when we call glimagetex2d the memory grow.

That above is reasonable,but when we use that texture for rendering, the memory grows again, and cause a system crash, memory not enough.

Will opengl alloc more memory, when we first use the texture for rendering?