From: Christoph Hellwig <hch@lst.de>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Juergen Gross <jgross@suse.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
intel-gfx@lists.freedesktop.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Chris Wilson <chris@chris-wilson.co.uk>,
linux-mm@kvack.org, dri-devel@lists.freedesktop.org,
xen-devel@lists.xenproject.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Christoph Hellwig <hch@lst.de>, Nitin Gupta <ngupta@vflare.org>,
Matthew Auld <matthew.auld@intel.com>
Subject: Re: [Intel-gfx] [PATCH 3/6] drm/i915: use vmap in shmem_pin_map
Date: Tue, 22 Sep 2020 16:31:41 +0200 [thread overview]
Message-ID: <20200922143141.GA26637@lst.de> (raw)
In-Reply-To: <43d10588-2033-038b-14e4-9f41cd622d7b@linux.intel.com>
On Tue, Sep 22, 2020 at 09:23:59AM +0100, Tvrtko Ursulin wrote:
> If I understood this sub-thread correctly, iterating and freeing the pages
> via the vmapped ptes, so no need for a
> shmem_read_mapping_page_gfp loop in shmem_unpin_map looks plausible to me.
>
> I did not get the reference to kernel/dma/remap.c though,
What I mean is the code in dma_common_find_pages, which returns the
page array for freeing.
>
> and also not sure
> how to do the error unwind path in shmem_pin_map at which point the
> allocated vm area hasn't been fully populated yet. Hand-roll the loop
> walking vm area struct in there?
Yes. What I originally did (re-created as I didn't save it) would be
something like this:
---
From 5605e77cda246df6dd7ded99ec22cb3f341ef5d5 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Wed, 16 Sep 2020 13:54:04 +0200
Subject: drm/i915: use vmap in shmem_pin_map
shmem_pin_map somewhat awkwardly reimplements vmap using
alloc_vm_area and manual pte setup. The only practical difference
is that alloc_vm_area prefeaults the vmalloc area PTEs, which doesn't
seem to be required here (and could be added to vmap using a flag
if actually required).
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/gpu/drm/i915/gt/shmem_utils.c | 81 +++++++++------------------
1 file changed, 27 insertions(+), 54 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.c b/drivers/gpu/drm/i915/gt/shmem_utils.c
index 43c7acbdc79dea..7ec6ba4c1065b2 100644
--- a/drivers/gpu/drm/i915/gt/shmem_utils.c
+++ b/drivers/gpu/drm/i915/gt/shmem_utils.c
@@ -49,80 +49,53 @@ struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
return file;
}
-static size_t shmem_npte(struct file *file)
+static size_t shmem_npages(struct file *file)
{
return file->f_mapping->host->i_size >> PAGE_SHIFT;
}
-static void __shmem_unpin_map(struct file *file, void *ptr, size_t n_pte)
-{
- unsigned long pfn;
-
- vunmap(ptr);
-
- for (pfn = 0; pfn < n_pte; pfn++) {
- struct page *page;
-
- page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
- GFP_KERNEL);
- if (!WARN_ON(IS_ERR(page))) {
- put_page(page);
- put_page(page);
- }
- }
-}
-
void *shmem_pin_map(struct file *file)
{
- const size_t n_pte = shmem_npte(file);
- pte_t *stack[32], **ptes, **mem;
- struct vm_struct *area;
- unsigned long pfn;
-
- mem = stack;
- if (n_pte > ARRAY_SIZE(stack)) {
- mem = kvmalloc_array(n_pte, sizeof(*mem), GFP_KERNEL);
- if (!mem)
- return NULL;
- }
+ size_t n_pages = shmem_npages(file), i;
+ struct page **pages;
+ void *vaddr;
- area = alloc_vm_area(n_pte << PAGE_SHIFT, mem);
- if (!area) {
- if (mem != stack)
- kvfree(mem);
+ pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
+ if (!pages)
return NULL;
- }
-
- ptes = mem;
- for (pfn = 0; pfn < n_pte; pfn++) {
- struct page *page;
- page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
- GFP_KERNEL);
- if (IS_ERR(page))
+ for (i = 0; i < n_pages; i++) {
+ pages[i] = shmem_read_mapping_page_gfp(file->f_mapping, i,
+ GFP_KERNEL);
+ if (IS_ERR(pages[i]))
goto err_page;
-
- **ptes++ = mk_pte(page, PAGE_KERNEL);
}
- if (mem != stack)
- kvfree(mem);
-
+ vaddr = vmap(pages, n_pages, 0, PAGE_KERNEL);
+ if (!vaddr)
+ goto err_page;
mapping_set_unevictable(file->f_mapping);
- return area->addr;
-
+ return vaddr;
err_page:
- if (mem != stack)
- kvfree(mem);
-
- __shmem_unpin_map(file, area->addr, pfn);
+ while (--i >= 0)
+ put_page(pages[i]);
+ kvfree(pages);
return NULL;
}
void shmem_unpin_map(struct file *file, void *ptr)
{
+ struct vm_struct *area = find_vm_area(ptr);
+ size_t i = shmem_npages(file);
+
+ if (WARN_ON_ONCE(!area || !area->pages))
+ return;
+
mapping_clear_unevictable(file->f_mapping);
- __shmem_unpin_map(file, ptr, shmem_npte(file));
+ for (i = 0; i < shmem_npages(file); i++)
+ put_page(area->pages[i]);
+ kvfree(area->pages);
+ vunmap(ptr);
}
static int __shmem_rw(struct file *file, loff_t off,
--
2.28.0
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next prev parent reply other threads:[~2020-09-22 14:32 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-18 16:37 [Intel-gfx] remove alloc_vm_area Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 1/6] zsmalloc: switch from alloc_vm_area to get_vm_area Christoph Hellwig
2020-09-21 17:42 ` Minchan Kim
2020-09-21 18:17 ` Christoph Hellwig
2020-09-21 18:42 ` Minchan Kim
2020-09-21 18:43 ` Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 2/6] mm: add a vmap_pfn function Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 3/6] drm/i915: use vmap in shmem_pin_map Christoph Hellwig
2020-09-21 19:11 ` Matthew Wilcox
2020-09-22 6:22 ` Christoph Hellwig
2020-09-22 8:23 ` Tvrtko Ursulin
2020-09-22 14:31 ` Christoph Hellwig [this message]
2020-09-22 16:13 ` Tvrtko Ursulin
2020-09-22 16:33 ` Christoph Hellwig
2020-09-22 17:04 ` Tvrtko Ursulin
2020-09-23 6:11 ` Christoph Hellwig
2020-09-22 11:21 ` Matthew Wilcox
2020-09-22 14:39 ` Christoph Hellwig
2020-09-22 14:53 ` Matthew Wilcox
2020-09-18 16:37 ` [Intel-gfx] [PATCH 4/6] drm/i915: use vmap in i915_gem_object_map Christoph Hellwig
2020-09-23 9:52 ` Tvrtko Ursulin
2020-09-23 13:41 ` Christoph Hellwig
2020-09-23 13:58 ` Tvrtko Ursulin
2020-09-23 14:44 ` Christoph Hellwig
2020-09-24 12:22 ` Tvrtko Ursulin
2020-09-24 13:23 ` Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 5/6] xen/xenbus: use apply_to_page_range directly in xenbus_map_ring_pv Christoph Hellwig
2020-09-18 16:37 ` [Intel-gfx] [PATCH 6/6] x86/xen: open code alloc_vm_area in arch_gnttab_valloc Christoph Hellwig
2020-09-21 20:44 ` boris.ostrovsky
2020-09-22 14:58 ` Christoph Hellwig
2020-09-22 15:24 ` boris.ostrovsky
2020-09-22 15:27 ` Christoph Hellwig
2020-09-22 15:34 ` boris.ostrovsky
2020-09-18 17:03 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area Patchwork
2020-09-21 17:50 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev2) Patchwork
2020-09-21 18:47 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev3) Patchwork
2020-09-22 14:44 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev4) Patchwork
2020-09-22 15:01 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for series starting with [1/6] zsmalloc: switch from alloc_vm_area to get_vm_area (rev5) Patchwork
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