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SubjectRe: BISECT result: 6.0.0-RC kernels trigger Firefox snap bug with 6.0.0-rc3 through 6.0.0-rc7
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On 10/18/22 09:15, Jintao Yin wrote:
> Hi Phillip,
> There is a logical bug in commit 8fc78b6fe24c36b151ac98d7546591ed92083d4f
> which is parent commit of commit b09a7a036d2035b14636cd4c4c69518d73770f65.
>
> In function squashfs_readahead(...),
> file_end is initialized with i_size_read(inode) >> msblk->block_log,
> which means the last block index of the file.
> But later in the logic to check if the page is last one or not the
> code is
> if (pages[nr_pages - 1]->index == file_end && bytes) {
> ...
> }
> , use file_end as the last page index of file but actually is the last
> block index, so for the common setup of page and block size, the first
> comparison is true only when pages[nr_pages - 1]->index is 0.
> Otherwise, the trailing bytes of last page won't be zeroed.
>
> Maybe it's the real cause of the snap bug in some way.
>

Hi Jintao, thanks for explaining the real culprit. However, I'd like to
see the fixup patch from you so that we can test.

Thanks.

--
An old man doll... just what I always wanted! - Clara

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