Subject: + drm-exynos-call-find_vma-with-the-mmap_sem-held.patch added to -mm tree To: zeus@xxxxxxx,airlied@xxxxxxxx,davidlohr@xxxxxx,inki.dae@xxxxxxxxxxx,jy0922.shim@xxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Mon, 21 Apr 2014 14:20:46 -0700 The patch titled Subject: drm/exynos: call find_vma with the mmap_sem held has been added to the -mm tree. Its filename is drm-exynos-call-find_vma-with-the-mmap_sem-held.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/drm-exynos-call-find_vma-with-the-mmap_sem-held.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/drm-exynos-call-find_vma-with-the-mmap_sem-held.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: Jonathan Gonzalez V <zeus@xxxxxxx> Subject: drm/exynos: call find_vma with the mmap_sem held Performing vma lookups without taking the mm->mmap_sem is asking for trouble. While doing the search, the vma in question can be modified or even removed before returning to the caller. Take the lock (exclusively) in order to avoid races while iterating through the vmacache and/or rbtree. Signed-off-by: Jonathan Gonzalez V <zeus@xxxxxxx> Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx> Cc: Inki Dae <inki.dae@xxxxxxxxxxx> Cc: Joonyoung Shim <jy0922.shim@xxxxxxxxxxx> Cc: David Airlie <airlied@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/exynos/exynos_drm_g2d.c | 6 ++++++ 1 file changed, 6 insertions(+) diff -puN drivers/gpu/drm/exynos/exynos_drm_g2d.c~drm-exynos-call-find_vma-with-the-mmap_sem-held drivers/gpu/drm/exynos/exynos_drm_g2d.c --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c~drm-exynos-call-find_vma-with-the-mmap_sem-held +++ a/drivers/gpu/drm/exynos/exynos_drm_g2d.c @@ -467,14 +467,17 @@ static dma_addr_t *g2d_userptr_get_dma_a goto err_free; } + down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, userptr); if (!vma) { + up_read(¤t->mm->mmap_sem); DRM_ERROR("failed to get vm region.\n"); ret = -EFAULT; goto err_free_pages; } if (vma->vm_end < userptr + size) { + up_read(¤t->mm->mmap_sem); DRM_ERROR("vma is too small.\n"); ret = -EFAULT; goto err_free_pages; @@ -482,6 +485,7 @@ static dma_addr_t *g2d_userptr_get_dma_a g2d_userptr->vma = exynos_gem_get_vma(vma); if (!g2d_userptr->vma) { + up_read(¤t->mm->mmap_sem); DRM_ERROR("failed to copy vma.\n"); ret = -ENOMEM; goto err_free_pages; @@ -492,10 +496,12 @@ static dma_addr_t *g2d_userptr_get_dma_a ret = exynos_gem_get_pages_from_userptr(start & PAGE_MASK, npages, pages, vma); if (ret < 0) { + up_read(¤t->mm->mmap_sem); DRM_ERROR("failed to get user pages from userptr.\n"); goto err_put_vma; } + up_read(¤t->mm->mmap_sem); g2d_userptr->pages = pages; sgt = kzalloc(sizeof(*sgt), GFP_KERNEL); _ Patches currently in -mm which might be from zeus@xxxxxxx are driverssgi-gru-grufaultc-call-find_vma-with-the-mmap_sem-held.patch drm-exynos-call-find_vma-with-the-mmap_sem-held.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