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charset="us-ascii" Content-Transfer-Encoding: 7bit > Index: linux-2.6/drivers/block/brd.c > =================================================================== > --- linux-2.6.orig/drivers/block/brd.c > +++ linux-2.6/drivers/block/brd.c > @@ -150,23 +150,27 @@ static void copy_to_brd(struct brd_devic > size_t copy; > > copy = min_t(size_t, n, PAGE_SIZE - offset); > + rcu_read_lock(); > page = brd_lookup_page(brd, sector); xa_load() inside brd_lookup_page() also calls rcu read lock. Instead of nesting rcu locks, could we modify the brd_lookup_page to use: diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 970bd6ff38c4..acc37bfdd181 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -55,7 +55,9 @@ static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) struct page *page; idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */ - page = xa_load(&brd->brd_pages, idx); + + XA_STATE(xas, &brd->brd_pages, idx); + page = xas_load(&xas); BUG_ON(page && page->index != idx); > BUG_ON(!page); > > dst = kmap_atomic(page); > memcpy(dst + offset, src, copy); > kunmap_atomic(dst); -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D7E0C0015E for ; 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charset="us-ascii" Content-Disposition: inline In-Reply-To: <7d99fa-9c13-ab2a-acde-1f8bbc63bf3@redhat.com> X-Originating-IP: [106.110.32.140] X-ClientProxiedBy: CAMSVWEXC01.scsc.local (2002:6a01:e347::6a01:e347) To CAMSVWEXC02.scsc.local (2002:6a01:e348::6a01:e348) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprBKsWRmVeSWpSXmKPExsWy7djP87r12odSDH61G1qsvtvPZvH+4GNW i73vZrNanJ6wiMniyvlZ7BZ7b2lbTOy4ymRx6d0yZgcOjy87+xk9Nq/Q8rh8ttSjt/kdm8f7 fVfZPD5vkgtgi+KySUnNySxLLdK3S+DKWPfmFXvBHM6K6Y1n2BsYt7B3MXJySAiYSJyY+o6l i5GLQ0hgBaPE+6+9jBDOF0aJnx9WglUJCXxmlLhwOQemY9+2i0wQRcsZJeZs2QTlABUt6D/O BuFsYZRoXnuUDaSFRUBVoqP5KlAVBwebgJZEYyfYVBEBTYlLc96wgtQzC0xgkvj8eg0LSEJY IFBi2YIpjCA2r4C5xNm9vWwQtqDEyZlPwGqYBXQkFuz+xAYyk1lAWmL5Pw6QMKeAtcSvH+1Q vylJNGw+wwJh10qc2nIL7FAJgQ8cEosWNzFCJFwkpm97xgphC0u8Og4LGBmJ/zvnM0HY1RJP b/xmhmhuYZTo37kebLEE0La+M9BgcZSY2DWDGSLMJ3HjrSDEmXwSk7ZNhwrzSnS0CUFUq0ms vveGZQKj8iwkj81C8tgshMcWMDKvYhRPLS3OTU8tNspLLdcrTswtLs1L10vOz93ECEw8p/8d /7KDcfmrj3qHGJk4GA8xSnAwK4nwGsbsSxHiTUmsrEotyo8vKs1JLT7EKM3BoiTOq217MllI ID2xJDU7NbUgtQgmy8TBKdXAVHti872C5l9TT/FEbbo1aWU23+n6KU4sXjHd8dNf7rwUrfN0 7pbYX2dSO5PfTms+KlJnvDLY1D3p67524T/3doTlNb08eel61O5zd6MmTj14UVc11YutIfPT lQ1bXmdt+Vv7Z1Giat/3dat+LLGds/Ph9zbWzR7rfs5IrQxNiuE3YPqmWfzv7WvJgBupLu9t TVlvFRbNCzn6ZnbNvDt3vimovT3yte3+t67d611mhoYudEkO1Wp1fbmsXbZ0iduX0vLWk1Uz RJc6qD42alfOfuNuKRRtFTTD69ST5+1/2382WeZuvvFvL8/Zj2bBGa5cLZM/yd+UYV64LPRa zteMqXIr833m3Jlqt0vu8fde7z1KLMUZiYZazEXFiQBEE+doqwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrKIsWRmVeSWpSXmKPExsVy+t/xe7r12odSDGZukbNYfbefzeL9wces FnvfzWa1OD1hEZPFlfOz2C323tK2mNhxlcni0rtlzA4cHl929jN6bF6h5XH5bKlHb/M7No/3 +66yeXzeJBfAFqVnU5RfWpKqkJFfXGKrFG1oYaRnaGmhZ2RiqWdobB5rZWSqpG9nk5Kak1mW WqRvl6CXse7NK/aCOZwV0xvPsDcwbmHvYuTkkBAwkdi37SJTFyMXh5DAUkaJphu9TBAJGYmN X66yQtjCEn+udbFBFH1klNgx+TErhLOFUeLOki/MIFUsAqoSHc1Xgbo5ONgEtCQaO8E2iAho Slya8wasnllgApPE9C8nwBLCAoESyxZMYQSxeQXMJc7u7WUD6RUSsJKY/zAGIiwocXLmExYQ m1lAR2LB7k9gJcwC0hLL/3GAhDkFrCV+/WiHekZJomHzGRYIu1bi899njBMYhWchmTQLyaRZ CJMWMDKvYhRJLS3OTc8tNtIrTswtLs1L10vOz93ECIy/bcd+btnBuPLVR71DjEwcjIcYJTiY lUR4DWP2pQjxpiRWVqUW5ccXleakFh9iNAUGxERmKdHkfGACyCuJNzQzMDU0MbM0MLU0M1YS 5/Us6EgUEkhPLEnNTk0tSC2C6WPi4JRqYNrad+CqglToVbfUZTGMVsEvz+7YKrdcqSBCfmmw +64Fl+zLf6snxX15Mls3S/ee5YVrYrdkOZflTlu6snuZo61gbfvey2d+9j/+GLVl4tXwf7b3 FruwnC5VzJ3JU+Me/iv57S5R3rhbRdsY1ucyJ+poXFlsZPJ6ZZD52ZxtvJF7VScdiDo6b7lJ 3b3y9H8rVFd6PFZcv/mUvYX5K876A/mT2fPe8kYtuvzm+bHDf6Nqck96TZuQsS3FboLj/Esx 3SzOl+/oPPldVCZ59JpOo03Ldf2VE0pqZ8+uunqw8paIv/KnL3PPvSnQDWGemRGQr9jMve/h 5hs7XZffmVOyaNuePw2vfL2NFu37Iii+/eUDJZbijERDLeai4kQAXxJwzkgDAAA= X-CMS-MailID: 20230727083159eucas1p1c4b907caac8371200bbd465143ac39fd X-Msg-Generator: CA X-RootMTR: 20230727083159eucas1p1c4b907caac8371200bbd465143ac39fd X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20230727083159eucas1p1c4b907caac8371200bbd465143ac39fd References: <7d99fa-9c13-ab2a-acde-1f8bbc63bf3@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org > Index: linux-2.6/drivers/block/brd.c > =================================================================== > --- linux-2.6.orig/drivers/block/brd.c > +++ linux-2.6/drivers/block/brd.c > @@ -150,23 +150,27 @@ static void copy_to_brd(struct brd_devic > size_t copy; > > copy = min_t(size_t, n, PAGE_SIZE - offset); > + rcu_read_lock(); > page = brd_lookup_page(brd, sector); xa_load() inside brd_lookup_page() also calls rcu read lock. Instead of nesting rcu locks, could we modify the brd_lookup_page to use: diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 970bd6ff38c4..acc37bfdd181 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -55,7 +55,9 @@ static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) struct page *page; idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */ - page = xa_load(&brd->brd_pages, idx); + + XA_STATE(xas, &brd->brd_pages, idx); + page = xas_load(&xas); BUG_ON(page && page->index != idx); > BUG_ON(!page); > > dst = kmap_atomic(page); > memcpy(dst + offset, src, copy); > kunmap_atomic(dst);