From 1461bc670ad19139b2815713e3e78c32476a1806 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Wed, 10 Feb 2021 11:45:42 -0500 Subject: [PATCH] fix: memcg: fix a crash in wb_workfn when a device disappears (5.6) See upstream commit: commit 68f23b89067fdf187763e75a56087550624fdbee ("memcg: fix a crash in wb_workfn when a device disappears") It is currently backported into stable branches 5.4 and 5.5, but appears to be missing from the 4.4, 4.9, 4.14, 4.19 LTS branches. Implement our own lttng_bdi_dev_name wrapper to provide this fix on builds against stable kernels which do not have this fix. There is one user-visible change with this commit: for builds against kernels < 4.4.0, the writeback_work_class events did use the default_backing_dev_info to handle cases where the device is NULL, writing "default" into the trace. This behavior is now aligned to match what is done in kernels >= 4.4.0, which is to write "(unknown)" into the name field. Link: https://lore.kernel.org/r/537870616.15400.1612973059419.JavaMail.zimbra@efficios.com> Signed-off-by: Mathieu Desnoyers Change-Id: I0823643aa2f9d4c2b9f2005748a2adfd4457979a --- .../events/lttng-module/writeback.h | 94 ++++++++----------- 1 file changed, 41 insertions(+), 53 deletions(-) diff --git a/instrumentation/events/lttng-module/writeback.h b/instrumentation/events/lttng-module/writeback.h index c173aad6..d6791e35 100644 --- a/instrumentation/events/lttng-module/writeback.h +++ b/instrumentation/events/lttng-module/writeback.h @@ -14,6 +14,22 @@ #ifndef _TRACE_WRITEBACK_DEF_ #define _TRACE_WRITEBACK_DEF_ +#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,6,0) || \ + LTTNG_KERNEL_RANGE(5,5,3, 5,6,0) || \ + LTTNG_KERNEL_RANGE(5,4,19, 5,5,0)) +static inline const char *lttng_bdi_dev_name(struct backing_dev_info *bdi) +{ + return bdi_dev_name(bdi); +} +#else +static inline const char *lttng_bdi_dev_name(struct backing_dev_info *bdi) +{ + if (!bdi || !bdi->dev) + return "(unknown)"; + return dev_name(bdi->dev); +} +#endif + /* * Vanilla kernels before 4.0 do not implement inode_to_bdi * RHEL kernels before 3.10.0-327.10.1 do not implement inode_to_bdi @@ -96,8 +112,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_dirty_page, TP_PROTO(struct page *page, struct address_space *mapping), TP_ARGS(page, mapping), TP_FIELDS( - ctf_string(name, - mapping ? dev_name(lttng_inode_to_bdi(mapping->host)->dev) : "(unknown)") + ctf_string(name, lttng_bdi_dev_name(mapping ? lttng_inode_to_bdi(mapping->host) : NULL)) ctf_integer(unsigned long, ino, mapping ? mapping->host->i_ino : 0) ctf_integer(pgoff_t, index, page->index) ) @@ -108,9 +123,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_dirty_inode_template, TP_ARGS(inode, flags), TP_FIELDS( /* may be called for files on pseudo FSes w/ unregistered bdi */ - ctf_string(name, - lttng_inode_to_bdi(inode)->dev ? - dev_name(lttng_inode_to_bdi(inode)->dev) : "(unknown)") + ctf_string(name, lttng_bdi_dev_name(lttng_inode_to_bdi(inode))) ctf_integer(unsigned long, ino, inode->i_ino) ctf_integer(unsigned long, state, inode->i_state) ctf_integer(unsigned long, flags, flags) @@ -128,8 +141,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_write_inode_template, TP_PROTO(struct inode *inode, struct writeback_control *wbc), TP_ARGS(inode, wbc), TP_FIELDS( - ctf_string(name, - dev_name(lttng_inode_to_bdi(inode)->dev)) + ctf_string(name, lttng_bdi_dev_name(lttng_inode_to_bdi(inode))) ctf_integer(unsigned long, ino, inode->i_ino) ctf_integer(int, sync_mode, wbc->sync_mode) ) @@ -148,8 +160,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_dirty_page, TP_PROTO(struct page *page, struct address_space *mapping), TP_ARGS(page, mapping), TP_FIELDS( - ctf_string(name, - mapping ? dev_name(mapping->backing_dev_info->dev) : "(unknown)") + ctf_string(name, lttng_bdi_dev_name(mapping ? mapping->backing_dev_info : NULL)) ctf_integer(unsigned long, ino, mapping ? mapping->host->i_ino : 0) ctf_integer(pgoff_t, index, page->index) ) @@ -160,10 +171,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_dirty_inode_template, TP_ARGS(inode, flags), TP_FIELDS( /* may be called for files on pseudo FSes w/ unregistered bdi */ - ctf_string(name, - inode->i_mapping->backing_dev_info->dev ? - dev_name(inode->i_mapping->backing_dev_info->dev) - : "(unknown)") + ctf_string(name, lttng_bdi_dev_name(inode->i_mapping->backing_dev_info)) ctf_integer(unsigned long, ino, inode->i_ino) ctf_integer(unsigned long, flags, flags) ) @@ -179,8 +187,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_write_inode_template, TP_PROTO(struct inode *inode, struct writeback_control *wbc), TP_ARGS(inode, wbc), TP_FIELDS( - ctf_string(name, - dev_name(inode->i_mapping->backing_dev_info->dev)) + ctf_string(name, lttng_bdi_dev_name(inode->i_mapping->backing_dev_info)) ctf_integer(unsigned long, ino, inode->i_ino) ctf_integer(int, sync_mode, wbc->sync_mode) ) @@ -201,35 +208,21 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_work_class, TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work), TP_ARGS(wb, work), TP_FIELDS( - ctf_string(name, wb->bdi->dev ? dev_name(wb->bdi->dev) : - "(unknown)") + ctf_string(name, lttng_bdi_dev_name(wb->bdi)) ) ) -#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,0,0)) - -LTTNG_TRACEPOINT_EVENT_CLASS(writeback_work_class, - TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work), - TP_ARGS(bdi, work), - TP_FIELDS( - ctf_string(name, bdi->dev ? dev_name(bdi->dev) : - "(unknown)") - ) -) - -#else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,0,0)) */ +#else LTTNG_TRACEPOINT_EVENT_CLASS(writeback_work_class, TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work), TP_ARGS(bdi, work), TP_FIELDS( - ctf_string(name, - dev_name(bdi->dev ? bdi->dev : - default_backing_dev_info.dev)) + ctf_string(name, lttng_bdi_dev_name(bdi)) ) ) -#endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,0,0)) */ +#endif /* #else if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,3,0)) */ #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,3,0)) @@ -270,8 +263,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_class, TP_PROTO(struct bdi_writeback *wb), TP_ARGS(wb), TP_FIELDS( - ctf_string(name, - dev_name(wb->bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(wb->bdi)) ) ) @@ -290,8 +282,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_bdi_register, TP_PROTO(struct backing_dev_info *bdi), TP_ARGS(bdi), TP_FIELDS( - ctf_string(name, - dev_name(bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(bdi)) ) ) @@ -301,8 +292,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_class, TP_PROTO(struct backing_dev_info *bdi), TP_ARGS(bdi), TP_FIELDS( - ctf_string(name, - dev_name(bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(bdi)) ) ) @@ -343,7 +333,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(balance_dirty_written, TP_ARGS(bdi, written), TP_FIELDS( - ctf_string(name, dev_name(bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(bdi)) ctf_integer(int, written, written) ) ) @@ -353,7 +343,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_wbc_class, TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi), TP_ARGS(wbc, bdi), TP_FIELDS( - ctf_string(name, dev_name(bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(bdi)) ctf_integer(long, nr_to_write, wbc->nr_to_write) ctf_integer(long, pages_skipped, wbc->pages_skipped) ctf_integer(int, sync_mode, wbc->sync_mode) @@ -401,7 +391,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_queue_io, int moved), TP_ARGS(wb, work, dirtied_before, moved), TP_FIELDS( - ctf_string(name, dev_name(wb->bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(wb->bdi)) ctf_integer(unsigned long, older, dirtied_before) ctf_integer(int, moved, moved) ) @@ -413,7 +403,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_queue_io, int moved), TP_ARGS(wb, work, moved), TP_FIELDS( - ctf_string(name, dev_name(wb->bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(wb->bdi)) ctf_integer(int, moved, moved) ) ) @@ -424,7 +414,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_queue_io, int moved), TP_ARGS(wb, older_than_this, moved), TP_FIELDS( - ctf_string(name, dev_name(wb->bdi->dev)) + ctf_string(name, lttng_bdi_dev_name(wb->bdi)) ctf_integer(unsigned long, older, older_than_this ? *older_than_this : 0) ctf_integer(long, age, @@ -526,7 +516,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(bdi_dirty_ratelimit, TP_ARGS(wb, dirty_rate, task_ratelimit), TP_FIELDS( - ctf_string(bdi, dev_name(wb->bdi->dev)) + ctf_string(bdi, lttng_bdi_dev_name(wb->bdi)) ctf_integer(unsigned long, write_bw, KBps(wb->bdi->wb.write_bandwidth)) ctf_integer(unsigned long, avg_write_bw, KBps(wb->bdi->wb.avg_write_bandwidth)) ctf_integer(unsigned long, dirty_rate, KBps(dirty_rate)) @@ -550,7 +540,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(bdi_dirty_ratelimit, TP_ARGS(bdi, dirty_rate, task_ratelimit), TP_FIELDS( - ctf_string(bdi, dev_name(bdi->dev)) + ctf_string(bdi, lttng_bdi_dev_name(bdi)) ctf_integer(unsigned long, write_bw, KBps(bdi->wb.write_bandwidth)) ctf_integer(unsigned long, avg_write_bw, KBps(bdi->wb.avg_write_bandwidth)) ctf_integer(unsigned long, dirty_rate, KBps(dirty_rate)) @@ -574,7 +564,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(bdi_dirty_ratelimit, TP_ARGS(bdi, dirty_rate, task_ratelimit), TP_FIELDS( - ctf_string(bdi, dev_name(bdi->dev)) + ctf_string(bdi, lttng_bdi_dev_name(bdi)) ctf_integer(unsigned long, write_bw, KBps(bdi->write_bandwidth)) ctf_integer(unsigned long, avg_write_bw, KBps(bdi->avg_write_bandwidth)) ctf_integer(unsigned long, dirty_rate, KBps(dirty_rate)) @@ -612,7 +602,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(balance_dirty_pages, ), TP_FIELDS( - ctf_string(bdi, dev_name(wb->bdi->dev)) + ctf_string(bdi, lttng_bdi_dev_name(wb->bdi)) ctf_integer(unsigned long, limit, global_dirty_limit) ctf_integer(unsigned long, setpoint, (global_dirty_limit + (thresh + bg_thresh) / 2) / 2) @@ -670,7 +660,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(balance_dirty_pages, ), TP_FIELDS( - ctf_string(bdi, dev_name(bdi->dev)) + ctf_string(bdi, lttng_bdi_dev_name(bdi)) ctf_integer(unsigned long, limit, global_dirty_limit) ctf_integer(unsigned long, setpoint, (global_dirty_limit + (thresh + bg_thresh) / 2) / 2) @@ -709,8 +699,7 @@ LTTNG_TRACEPOINT_EVENT(writeback_sb_inodes_requeue, TP_ARGS(inode), TP_FIELDS( - ctf_string(name, - dev_name(lttng_inode_to_bdi(inode)->dev)) + ctf_string(name, lttng_bdi_dev_name(lttng_inode_to_bdi(inode))) ctf_integer(unsigned long, ino, inode->i_ino) ctf_integer(unsigned long, state, inode->i_state) ctf_integer(unsigned long, dirtied_when, inode->dirtied_when) @@ -757,8 +746,7 @@ LTTNG_TRACEPOINT_EVENT_CLASS(writeback_single_inode_template, TP_ARGS(inode, wbc, nr_to_write), TP_FIELDS( - ctf_string(name, - dev_name(lttng_inode_to_bdi(inode)->dev)) + ctf_string(name, lttng_bdi_dev_name(lttng_inode_to_bdi(inode))) ctf_integer(unsigned long, ino, inode->i_ino) ctf_integer(unsigned long, state, inode->i_state) ctf_integer(unsigned long, dirtied_when, inode->dirtied_when) -- 2.34.1