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Date: Thu, 20 Oct 2022 20:02:02 +0700
From: Bagas Sanjaya <bagasdotme@...il.com>
To: Jintao Yin <nicememory@...il.com>, phillip@...ashfs.org.uk
Cc: hsinyi@...omium.org, linux-kernel@...r.kernel.org,
marcmiltenberger@...il.com, mirsad.todorovac@....unizg.hr,
regressions@...mhuis.info, regressions@...ts.linux.dev,
srw@...dewatkins.net
Subject: Re: BISECT result: 6.0.0-RC kernels trigger Firefox snap bug with
6.0.0-rc3 through 6.0.0-rc7
On 10/20/22 14:43, Jintao Yin wrote:
> Ignore my before diff. I didn't notice the end_index caculation greater
> than file_end part. Use the following diff instead.
>
> This diff is based on Phillip's latest two patches and improves the logic
> to update the status of pages only if page actor touches them.
>
> Please help test and feedbacks are welcome.
>
> Thanks,
>
> Jintao
>
> diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
> index e56510964b22..5efa2a9f9630 100644
> --- a/fs/squashfs/file.c
> +++ b/fs/squashfs/file.c
> @@ -506,8 +506,9 @@ static int squashfs_readahead_fragment(struct page **page,
> squashfs_i(inode)->fragment_size);
> struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
> + int res = buffer->error;
>
> - if (buffer->error)
> + if (res)
> goto out;
>
> expected += squashfs_i(inode)->fragment_offset;
> @@ -529,7 +530,7 @@ static int squashfs_readahead_fragment(struct page **page,
>
> out:
> squashfs_cache_put(buffer);
> - return buffer->error;
> + return res;
> }
>
> static void squashfs_readahead(struct readahead_control *ractl)
> @@ -557,6 +558,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
> int res, bsize;
> u64 block = 0;
> unsigned int expected;
> + int nr_used_pages;
>
> nr_pages = __readahead_batch(ractl, pages, max_pages);
> if (!nr_pages)
> @@ -593,18 +595,18 @@ static void squashfs_readahead(struct readahead_control *ractl)
>
> res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
>
> - squashfs_page_actor_free(actor);
> + nr_used_pages = squashfs_page_actor_free(actor);
>
> if (res == expected) {
> int bytes;
>
> /* Last page (if present) may have trailing bytes not filled */
> bytes = res % PAGE_SIZE;
> - if (pages[nr_pages - 1]->index == file_end && bytes)
> - memzero_page(pages[nr_pages - 1], bytes,
> + if (index == file_end && bytes && nr_used_pages > 0)
> + memzero_page(pages[nr_used_pages - 1], bytes,
> PAGE_SIZE - bytes);
>
> - for (i = 0; i < nr_pages; i++) {
> + for (i = 0; i < nr_used_pages; i++) {
> flush_dcache_page(pages[i]);
> SetPageUptodate(pages[i]);
> }
> diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
> index f1ccad519e28..1bb0347f98b0 100644
> --- a/fs/squashfs/file_direct.c
> +++ b/fs/squashfs/file_direct.c
> @@ -30,10 +30,9 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
> int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
> int start_index = target_page->index & ~mask;
> int end_index = start_index | mask;
> - int i, n, pages, bytes, res = -ENOMEM;
> + int i, n, pages, used_pages, bytes, res = -ENOMEM;
> struct page **page;
> struct squashfs_page_actor *actor;
> - void *pageaddr;
>
> if (end_index > file_end)
> end_index = file_end;
> @@ -74,7 +73,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
> /* Decompress directly into the page cache buffers */
> res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
>
> - squashfs_page_actor_free(actor);
> + used_pages = squashfs_page_actor_free(actor);
>
> if (res < 0)
> goto mark_errored;
> @@ -86,16 +85,18 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
>
> /* Last page (if present) may have trailing bytes not filled */
> bytes = res % PAGE_SIZE;
> - if (page[pages - 1]->index == end_index && bytes) {
> - pageaddr = kmap_local_page(page[pages - 1]);
> - memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
> - kunmap_local(pageaddr);
> + if (used_pages > 0 && page[used_pages - 1]->index == end_index &&
> + bytes) {
> + memzero_page(page[used_pages - 1], bytes,
> + PAGE_SIZE - bytes);
> }
>
> /* Mark pages as uptodate, unlock and release */
> for (i = 0; i < pages; i++) {
> - flush_dcache_page(page[i]);
> - SetPageUptodate(page[i]);
> + if (i < used_pages) {
> + flush_dcache_page(page[i]);
> + SetPageUptodate(page[i]);
> + }
> unlock_page(page[i]);
> if (page[i] != target_page)
> put_page(page[i]);
> @@ -112,8 +113,10 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
> for (i = 0; i < pages; i++) {
> if (page[i] == NULL || page[i] == target_page)
> continue;
> - flush_dcache_page(page[i]);
> - SetPageError(page[i]);
> + if (i < used_pages) {
> + flush_dcache_page(page[i]);
> + SetPageError(page[i]);
> + }
> unlock_page(page[i]);
> put_page(page[i]);
> }
> diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h
> index 95ffbb543d91..c2c5c3937ef9 100644
> --- a/fs/squashfs/page_actor.h
> +++ b/fs/squashfs/page_actor.h
> @@ -29,10 +29,12 @@ extern struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
> extern struct squashfs_page_actor *squashfs_page_actor_init_special(
> struct squashfs_sb_info *msblk,
> struct page **page, int pages, int length);
> -static inline void squashfs_page_actor_free(struct squashfs_page_actor *actor)
> +static inline int squashfs_page_actor_free(struct squashfs_page_actor *actor)
> {
> + int res = actor->next_page;
> kfree(actor->tmp_buffer);
> kfree(actor);
> + return res;
> }
> static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
> {
Hi Jintao,
Booting v6.1-rc1 with your patch applied, I got mixed results. On hello-world
snap, it runs without errors. On lxd, I got the Verneed regression as
originally reported. Sometimes I also get snapd panic.
Thanks.
--
An old man doll... just what I always wanted! - Clara
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