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xen/grant-table: Use put_page instead of free_page
[ Upstream commit 3ac7292a25
]
The page given to gnttab_end_foreign_access() to free could be a
compound page so use put_page() instead of free_page() since it can
handle both compound and single pages correctly.
This bug was discovered when migrating a Xen VM with several VIFs and
CONFIG_DEBUG_VM enabled. It hits a BUG usually after fewer than 10
iterations. All netfront devices disconnect from the backend during a
suspend/resume and this will call gnttab_end_foreign_access() if a
netfront queue has an outstanding skb. The mismatch between calling
get_page() and free_page() on a compound page causes a reference
counting error which is detected when DEBUG_VM is enabled.
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
70f3461c23
commit
05c062c368
1 changed files with 2 additions and 2 deletions
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@ -328,7 +328,7 @@ static void gnttab_handle_deferred(unsigned long unused)
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if (entry->page) {
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pr_debug("freeing g.e. %#x (pfn %#lx)\n",
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entry->ref, page_to_pfn(entry->page));
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__free_page(entry->page);
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put_page(entry->page);
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} else
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pr_info("freeing g.e. %#x\n", entry->ref);
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kfree(entry);
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@ -384,7 +384,7 @@ void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
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if (gnttab_end_foreign_access_ref(ref, readonly)) {
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put_free_entry(ref);
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if (page != 0)
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free_page(page);
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put_page(virt_to_page(page));
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} else
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gnttab_add_deferred(ref, readonly,
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page ? virt_to_page(page) : NULL);
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