Re: [PATCH] Remove unnecessary calls to kmap{,_local_page}() when acquiring pages using GFP_DMA32.
Sumitra Sharma wrote: > The GFP_DMA32 uses the DMA32 zone to satisfy the allocation > requests. Therefore, pages allocated with GFP_DMA32 cannot > come from Highmem. > > Avoid using calls to kmap() / kunmap() as the kmap() is being > deprecated [1]. > > Avoid using calls to kmap_local_page() / kunmap_local() as the > code does not depends on the implicit disable of migration of > local mappings and is, in fact, an unnecessary overhead for > the main code [2]. > > Hence, use a plain page_address() directly in the > psb_mmu_alloc_pd function. > > [1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.we...@intel.com/ > [2]: https://lwn.net/Articles/836503/ > > Suggested-by: Ira Weiny Reviewed-by: Ira Weiny > Signed-off-by: Sumitra Sharma > --- > drivers/gpu/drm/gma500/mmu.c | 11 +++ > 1 file changed, 3 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/gma500/mmu.c b/drivers/gpu/drm/gma500/mmu.c > index a70b01ccdf70..1a44dd062fd1 100644 > --- a/drivers/gpu/drm/gma500/mmu.c > +++ b/drivers/gpu/drm/gma500/mmu.c > @@ -184,20 +184,15 @@ struct psb_mmu_pd *psb_mmu_alloc_pd(struct > psb_mmu_driver *driver, > pd->invalid_pte = 0; > } > > - v = kmap_local_page(pd->dummy_pt); > + v = page_address(pd->dummy_pt); > for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i) > v[i] = pd->invalid_pte; > > - kunmap_local(v); > - > - v = kmap_local_page(pd->p); > + v = page_address(pd->p); > for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i) > v[i] = pd->invalid_pde; > > - kunmap_local(v); > - > - clear_page(kmap(pd->dummy_page)); > - kunmap(pd->dummy_page); > + clear_page(page_address(pd->dummy_page)); > > pd->tables = vmalloc_user(sizeof(struct psb_mmu_pt *) * 1024); > if (!pd->tables) > -- > 2.25.1 >
[PATCH] Remove unnecessary calls to kmap{,_local_page}() when acquiring pages using GFP_DMA32.
The GFP_DMA32 uses the DMA32 zone to satisfy the allocation requests. Therefore, pages allocated with GFP_DMA32 cannot come from Highmem. Avoid using calls to kmap() / kunmap() as the kmap() is being deprecated [1]. Avoid using calls to kmap_local_page() / kunmap_local() as the code does not depends on the implicit disable of migration of local mappings and is, in fact, an unnecessary overhead for the main code [2]. Hence, use a plain page_address() directly in the psb_mmu_alloc_pd function. [1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.we...@intel.com/ [2]: https://lwn.net/Articles/836503/ Suggested-by: Ira Weiny Signed-off-by: Sumitra Sharma --- drivers/gpu/drm/gma500/mmu.c | 11 +++ 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/gma500/mmu.c b/drivers/gpu/drm/gma500/mmu.c index a70b01ccdf70..1a44dd062fd1 100644 --- a/drivers/gpu/drm/gma500/mmu.c +++ b/drivers/gpu/drm/gma500/mmu.c @@ -184,20 +184,15 @@ struct psb_mmu_pd *psb_mmu_alloc_pd(struct psb_mmu_driver *driver, pd->invalid_pte = 0; } - v = kmap_local_page(pd->dummy_pt); + v = page_address(pd->dummy_pt); for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i) v[i] = pd->invalid_pte; - kunmap_local(v); - - v = kmap_local_page(pd->p); + v = page_address(pd->p); for (i = 0; i < (PAGE_SIZE / sizeof(uint32_t)); ++i) v[i] = pd->invalid_pde; - kunmap_local(v); - - clear_page(kmap(pd->dummy_page)); - kunmap(pd->dummy_page); + clear_page(page_address(pd->dummy_page)); pd->tables = vmalloc_user(sizeof(struct psb_mmu_pt *) * 1024); if (!pd->tables) -- 2.25.1
