As reported in the community forum [0], there currently is a memory leak in the CIFS client code. Reproduced by running a backup with CIFS target storage:
> while true; do vzdump 101 --storage cifs --prune-backups keep-last=1; echo 3 > > /proc/sys/vm/drop_caches; done A fix was found on the kernel mailing list tagged for stable v6.6+ and it does solve the issue, but is not yet included in any (stable) kernels. [0]: https://forum.proxmox.com/threads/147603/post-682388 Signed-off-by: Fiona Ebner <f.eb...@proxmox.com> --- ...ix-pagecache-leak-when-do-writepages.patch | 108 ++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 patches/kernel/0018-cifs-fix-pagecache-leak-when-do-writepages.patch diff --git a/patches/kernel/0018-cifs-fix-pagecache-leak-when-do-writepages.patch b/patches/kernel/0018-cifs-fix-pagecache-leak-when-do-writepages.patch new file mode 100644 index 0000000..495dd71 --- /dev/null +++ b/patches/kernel/0018-cifs-fix-pagecache-leak-when-do-writepages.patch @@ -0,0 +1,108 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: Yang Erkun <yanger...@huawei.com> +Date: Tue, 25 Jun 2024 11:43:32 +0800 +Subject: [PATCH] cifs: fix pagecache leak when do writepages + +After commit f3dc1bdb6b0b("cifs: Fix writeback data corruption"), the +writepages for cifs will find all folio needed writepage with two phase. +The first folio will be found in cifs_writepages_begin, and the latter +various folios will be found in cifs_extend_writeback. + +All those will first get folio, and for normal case, once we set page +writeback and after do really write, we should put the reference, folio +found in cifs_extend_writeback do this with folio_batch_release. But the +folio found in cifs_writepages_begin never get the chance do it. And +every writepages call, we will leak a folio(found this problem while do +xfstests over cifs, the latter show that we will leak about 600M+ every +we run generic/074). + +echo 3 > /proc/sys/vm/drop_caches ; cat /proc/meminfo | grep file +Active(file): 34092 kB +Inactive(file): 176192 kB +./check generic/074 (smb v1) +... +generic/074 50s ... 53s +Ran: generic/074 +Passed all 1 tests + +echo 3 > /proc/sys/vm/drop_caches ; cat /proc/meminfo | grep file +Active(file): 35036 kB +Inactive(file): 854708 kB + +Besides, the exist path seem never handle this folio correctly, fix it too +with this patch. + +The problem does not exist in mainline since writepages path for cifs +has changed to netfs(3ee1a1fc3981 ("cifs: Cut over to using netfslib")). +It's had to backport all related change, so try fix this problem with this +single patch. + +Fixes: f3dc1bdb6b0b ("cifs: Fix writeback data corruption") +Cc: sta...@kernel.org # v6.6+ +Signed-off-by: Yang Erkun <yanger...@huawei.com> +(picked from https://lore.kernel.org/linux-cifs/20240625034332.750312-1-yanger...@huawei.com/) +Signed-off-by: Fiona Ebner <f.eb...@proxmox.com> +--- + fs/smb/client/file.c | 16 +++++++++++++--- + 1 file changed, 13 insertions(+), 3 deletions(-) + +diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c +index af5c476db6e6..8aee0f520300 100644 +--- a/fs/smb/client/file.c ++++ b/fs/smb/client/file.c +@@ -2845,17 +2845,21 @@ static ssize_t cifs_write_back_from_locked_folio(struct address_space *mapping, + rc = cifs_get_writable_file(CIFS_I(inode), FIND_WR_ANY, &cfile); + if (rc) { + cifs_dbg(VFS, "No writable handle in writepages rc=%d\n", rc); ++ folio_unlock(folio); + goto err_xid; + } + + rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->wsize, + &wsize, credits); +- if (rc != 0) ++ if (rc != 0) { ++ folio_unlock(folio); + goto err_close; ++ } + + wdata = cifs_writedata_alloc(cifs_writev_complete); + if (!wdata) { + rc = -ENOMEM; ++ folio_unlock(folio); + goto err_uncredit; + } + +@@ -3002,17 +3006,22 @@ static ssize_t cifs_writepages_begin(struct address_space *mapping, + lock_again: + if (wbc->sync_mode != WB_SYNC_NONE) { + ret = folio_lock_killable(folio); +- if (ret < 0) ++ if (ret < 0) { ++ folio_put(folio); + return ret; ++ } + } else { +- if (!folio_trylock(folio)) ++ if (!folio_trylock(folio)) { ++ folio_put(folio); + goto search_again; ++ } + } + + if (folio->mapping != mapping || + !folio_test_dirty(folio)) { + start += folio_size(folio); + folio_unlock(folio); ++ folio_put(folio); + goto search_again; + } + +@@ -3042,6 +3051,7 @@ static ssize_t cifs_writepages_begin(struct address_space *mapping, + out: + if (ret > 0) + *_start = start + ret; ++ folio_put(folio); + return ret; + } + -- 2.39.2 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
