在 2022/11/4 14:25, Jiri Slaby 写道:

On 04. 11. 22, 6:41, TGSP wrote:

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From: xiongxin xiongxin@kylinos.cn

Added a check on the return value of preallocate_image_highmem(). If memory preallocate is insufficient, S4 cannot be done;

I am playing 4K video on a machine with AMD or other graphics card and only 8GiB memory, and the kernel is not configured with CONFIG_HIGHMEM. When doing the S4 test, the analysis found that when the pages get from minimum_image_size() is large enough, The preallocate_image_memory() and preallocate_image_highmem() calls failed to obtain enough memory. Add the judgment that memory preallocate is insufficient;

The detailed debugging data is as follows:

image_size: 3225923584, totalram_pages: 1968948 in hibernate_reserved_size_init();

in hibernate_preallocate_memory(): code pages = minimum_image_size(saveable) = 717992, at this time(line): count: 2030858 avail_normal: 2053753 highmem: 0 totalreserve_pages: 22895 max_size: 1013336 size: 787579 saveable: 1819905

When the code executes to: pages = preallocate_image_memory(alloc, avail_normal), at that time(line): pages_highmem: 0 avail_normal: 1335761 alloc: 1017522 pages: 1017522

So enter the else branch judged by (pages < alloc), When executed to size = preallocate_image_memory(alloc, avail_normal): alloc = max_size - size = 225757; size = preallocate_image_memory(alloc, avail_normal) = 168671, That is, preallocate_image_memory() does not apply for all alloc memory pages, because highmem is not enabled, and size_highmem will return 0 here, so there is a memory page that has not been preallocated, so I think a judgment needs to be added here.

But what I can't understand is that although pages are not preallocated enough, "pages -= free_unnecessary_pages()" in the code below can also discard some pages that have been preallocated, so I am not sure whether it is appropriate to add a judgment here.

Cc: stable@vger.kernel.org Signed-off-by: xiongxin xiongxin@kylinos.cn Signed-off-by: huanglei huanglei@kylinos.cn

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kernel/power/snapshot.c | 11 +++++++++--   1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index c20ca5fb9adc..546d544cf7de 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1854,6 +1854,8 @@ int hibernate_preallocate_memory(void)           alloc = (count - pages) - size;           pages += preallocate_image_highmem(alloc);       } else { +        unsigned long size_highmem = 0;

This needs not be initialized, right?

If there is no need to make judgments here, then in the (pages < alloc) branch, it is necessary to make judgments on (pages_highmem < alloc)? should be the same;

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@@ -1863,8 +1865,13 @@ int hibernate_preallocate_memory(void)           pages_highmem += size;           alloc -= size;           size = preallocate_image_memory(alloc, avail_normal); -        pages_highmem += preallocate_image_highmem(alloc - size); -        pages += pages_highmem + size; +        size_highmem = preallocate_image_highmem(alloc - size); +        if (size_highmem < (alloc - size)) { +            pr_err("Image allocation is %lu pages short, exit\n", +                alloc - size - pages_highmem); +            goto err_out; +        } +        pages += pages_highmem + size_highmem + size;       }       /*