From: Andrew Morton <akpm@linux-foundation.org>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-mm@kvack.org, Song Liu <songliubraving@fb.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Qian Cai <cai@lca.pw>
Subject: Re: [PATCH 0/3] Fix read-only THP for non-tmpfs filesystems
Date: Fri, 4 Sep 2020 10:23:36 -0700 [thread overview]
Message-ID: <20200904102336.9ac7fd0ce0956b177cd760c9@linux-foundation.org> (raw)
In-Reply-To: <20200903183029.14930-1-willy@infradead.org>
On Thu, 3 Sep 2020 19:30:26 +0100 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
> As described more verbosely in the [3/3] changelog, we can
> inadvertently put an order-0 page in the page cache which
> occupies 512 consecutive entries. Users are running into
> this if they enable the READ_ONLY_THP_FOR_FS config option;
> see https://bugzilla.kernel.org/show_bug.cgi?id=206569
> and Qian Cai has also reported it here:
> https://lore.kernel.org/lkml/20200616013309.GB815@lca.pw/
>
> This is a rather intrusive way of fixing the problem, but has the
> advantage that I've actually been testing it with the THP patches,
> which means that it sees far more use than it does upstream -- indeed,
> Song has been entirely unable to reproduce it. It also has the advantage
> that it removes a few patches from my gargantuan backlog of THP patches.
ERROR: modpost: "xa_get_order" [lib/test_xarray.ko] undefined!
ERROR: modpost: "xas_split_alloc" [lib/test_xarray.ko] undefined!
xarray is an odd mixture of EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL(). I
did this:
--- a/lib/xarray.c~xarray-add-xas_split-fix
+++ a/lib/xarray.c
@@ -1025,6 +1025,7 @@ nomem:
xas_destroy(xas);
xas_set_err(xas, -ENOMEM);
}
+EXPORT_SYMBOL_GPL(xas_split_alloc);
/**
* xas_split() - Split a multi-index entry into smaller entries.
_
and
--- a/lib/xarray.c~xarray-add-xa_get_order-fix
+++ a/lib/xarray.c
@@ -1631,6 +1631,7 @@ unlock:
return order;
}
+EXPORT_SYMBOL(xa_get_order);
#endif /* CONFIG_XARRAY_MULTI */
/**
_
prev parent reply other threads:[~2020-09-04 18:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 18:30 [PATCH 0/3] Fix read-only THP for non-tmpfs filesystems Matthew Wilcox (Oracle)
2020-09-03 18:30 ` [PATCH 1/3] XArray: Add xa_get_order Matthew Wilcox (Oracle)
2020-09-03 18:30 ` [PATCH 2/3] XArray: Add xas_split Matthew Wilcox (Oracle)
2020-09-03 18:30 ` [PATCH 3/3] mm/filemap: Fix storing to a THP shadow entry Matthew Wilcox (Oracle)
2020-09-04 17:23 ` Andrew Morton [this message]
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