On 2017/12/23 13:32, Xishi Qiu wrote: > On 2017/12/21 16:55, Xishi Qiu wrote: > >> When we use iounmap() to free the mapping, it calls unmap_vmap_area() to >> clear page table, >> but do not free the memory of page table, right? >> >> So when use ioremap() to mapping another area(incluce the area before), it >> may use >> large mapping(e.g. ioremap_pmd_enabled()), so the original page table >> memory(e.g. pte memory) >> will be lost, it cause memory leak, right? > > > > So I have two questions for this scene. > > 1. When the same virtual address allocated from ioremap, first is 4K size, > second is 2M size, if Kernel would leak memory. > > 2. Kernel modifies the old invalid 4K pagetable to 2M, but doesn`t follow the > ARM break-before-make flow, CPU maybe get the old invalid 4K pagetable > information, then Kernel would panic.
I sent a RFC patch for this one [1]. [1]: https://patchwork.kernel.org/patch/10134581/ Thanks Hanjun
