From f1e67e355c2aafeddf1eac31335709236996d2fe Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 18 Nov 2019 14:28:24 +0100 Subject: fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t Bit spinlocks are problematic if PREEMPT_RT is enabled, because they disable preemption, which is undesired for latency reasons and breaks when regular spinlocks are taken within the bit_spinlock locked region because regular spinlocks are converted to 'sleeping spinlocks' on RT. PREEMPT_RT replaced the bit spinlocks with regular spinlocks to avoid this problem. The replacement was done conditionaly at compile time, but Christoph requested to do an unconditional conversion. Jan suggested to move the spinlock into a existing padding hole which avoids a size increase of struct buffer_head on production kernels. As a benefit the lock gains lockdep coverage. [ bigeasy: Remove the wrapper and use always spinlock_t and move it into the padding hole ] Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Reviewed-by: Jan Kara Cc: Christoph Hellwig Link: https://lkml.kernel.org/r/20191118132824.rclhrbujqh4b4g4d@linutronix.de --- include/linux/buffer_head.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/buffer_head.h') diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 7b73ef7f902d..e0b020eaf32e 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -22,9 +22,6 @@ enum bh_state_bits { BH_Dirty, /* Is dirty */ BH_Lock, /* Is locked */ BH_Req, /* Has been submitted for I/O */ - BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise - * IO completion of other buffers in the page - */ BH_Mapped, /* Has a disk mapping */ BH_New, /* Disk mapping was newly created by get_block */ @@ -76,6 +73,9 @@ struct buffer_head { struct address_space *b_assoc_map; /* mapping this buffer is associated with */ atomic_t b_count; /* users using this buffer_head */ + spinlock_t b_uptodate_lock; /* Used by the first bh in a page, to + * serialise IO completion of other + * buffers in the page */ }; /* -- cgit v1.2.3 From d87f639258a6a5980183f11876c884931ad93da2 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Fri, 28 Feb 2020 16:14:11 -0800 Subject: ext4: use non-movable memory for superblock readahead Since commit a8ac900b8163 ("ext4: use non-movable memory for the superblock") buffers for ext4 superblock were allocated using the sb_bread_unmovable() helper which allocated buffer heads out of non-movable memory blocks. It was necessarily to not block page migrations and do not cause cma allocation failures. However commit 85c8f176a611 ("ext4: preload block group descriptors") broke this by introducing pre-reading of the ext4 superblock. The problem is that __breadahead() is using __getblk() underneath, which allocates buffer heads out of movable memory. It resulted in page migration failures I've seen on a machine with an ext4 partition and a preallocated cma area. Fix this by introducing sb_breadahead_unmovable() and __breadahead_gfp() helpers which use non-movable memory for buffer head allocations and use them for the ext4 superblock readahead. Reviewed-by: Andreas Dilger Fixes: 85c8f176a611 ("ext4: preload block group descriptors") Signed-off-by: Roman Gushchin Link: https://lore.kernel.org/r/20200229001411.128010-1-guro@fb.com Signed-off-by: Theodore Ts'o --- include/linux/buffer_head.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/buffer_head.h') diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index e0b020eaf32e..15b765a181b8 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -189,6 +189,8 @@ struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block, void __brelse(struct buffer_head *); void __bforget(struct buffer_head *); void __breadahead(struct block_device *, sector_t block, unsigned int size); +void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size, + gfp_t gfp); struct buffer_head *__bread_gfp(struct block_device *, sector_t block, unsigned size, gfp_t gfp); void invalidate_bh_lrus(void); @@ -319,6 +321,12 @@ sb_breadahead(struct super_block *sb, sector_t block) __breadahead(sb->s_bdev, block, sb->s_blocksize); } +static inline void +sb_breadahead_unmovable(struct super_block *sb, sector_t block) +{ + __breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0); +} + static inline struct buffer_head * sb_getblk(struct super_block *sb, sector_t block) { -- cgit v1.2.3