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 --- fs/ext4/inode.c | 2 +- fs/ext4/super.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 68f6c0af8e5d..2a4aae6acdcb 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4364,7 +4364,7 @@ make_io: if (end > table) end = table; while (b <= end) - sb_breadahead(sb, b++); + sb_breadahead_unmovable(sb, b++); } /* diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 9728e7b0e84f..83413f0f1e28 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4340,7 +4340,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) /* Pre-read the descriptors into the buffer cache */ for (i = 0; i < db_count; i++) { block = descriptor_loc(sb, logical_sb_block, i); - sb_breadahead(sb, block); + sb_breadahead_unmovable(sb, block); } for (i = 0; i < db_count; i++) { -- cgit v1.2.3-70-g09d2