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mm: Add kvrealloc()

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During log recovery of an XFS filesystem with 64kB directory
buffers, rebuilding a buffer split across two log records results
in a memory allocation warning from krealloc like this:

xfs filesystem being mounted at /mnt/scratch supports timestamps until 2038 (0x7fffffff)
XFS (dm-0): Unmounting Filesystem
XFS (dm-0): Mounting V5 Filesystem
XFS (dm-0): Starting recovery (logdev: internal)
------------[ cut here ]------------
WARNING: CPU: 5 PID: 3435170 at mm/page_alloc.c:3539 get_page_from_freelist+0xdee/0xe40
.....
RIP: 0010:get_page_from_freelist+0xdee/0xe40
Call Trace:
 ? complete+0x3f/0x50
 __alloc_pages+0x16f/0x300
 alloc_pages+0x87/0x110
 kmalloc_order+0x2c/0x90
 kmalloc_order_trace+0x1d/0x90
 __kmalloc_track_caller+0x215/0x270
 ? xlog_recover_add_to_cont_trans+0x63/0x1f0
 krealloc+0x54/0xb0
 xlog_recover_add_to_cont_trans+0x63/0x1f0
 xlog_recovery_process_trans+0xc1/0xd0
 xlog_recover_process_ophdr+0x86/0x130
 xlog_recover_process_data+0x9f/0x160
 xlog_recover_process+0xa2/0x120
 xlog_do_recovery_pass+0x40b/0x7d0
 ? __irq_work_queue_local+0x4f/0x60
 ? irq_work_queue+0x3a/0x50
 xlog_do_log_recovery+0x70/0x150
 xlog_do_recover+0x38/0x1d0
 xlog_recover+0xd8/0x170
 xfs_log_mount+0x181/0x300
 xfs_mountfs+0x4a1/0x9b0
 xfs_fs_fill_super+0x3c0/0x7b0
 get_tree_bdev+0x171/0x270
 ? suffix_kstrtoint.constprop.0+0xf0/0xf0
 xfs_fs_get_tree+0x15/0x20
 vfs_get_tree+0x24/0xc0
 path_mount+0x2f5/0xaf0
 __x64_sys_mount+0x108/0x140
 do_syscall_64+0x3a/0x70
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Essentially, we are taking a multi-order allocation from kmem_alloc()
(which has an open coded no fail, no warn loop) and then
reallocating it out to 64kB using krealloc(__GFP_NOFAIL) and that is
then triggering the above warning.

This is a regression caused by converting this code from an open
coded no fail/no warn reallocation loop to using __GFP_NOFAIL.

What we actually need here is kvrealloc(), so that if contiguous
page allocation fails we fall back to vmalloc() and we don't
get nasty warnings happening in XFS.

Fixes: 771915c4f6 ("xfs: remove kmem_realloc()")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Dave Chinner 2021-08-09 10:10:00 -07:00 committed by Darrick J. Wong
parent 43059d5416
commit de2860f463
3 changed files with 20 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/xfs/xfs_log_recover.c
View File

@ -2062,7 +2062,9 @@ xlog_recover_add_to_cont_trans(
old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
old_len = item->ri_buf[item->ri_cnt-1].i_len;
ptr = krealloc(old_ptr, len + old_len, GFP_KERNEL | __GFP_NOFAIL);
ptr = kvrealloc(old_ptr, old_len, len + old_len, GFP_KERNEL);
if (!ptr)
return -ENOMEM;
memcpy(&ptr[old_len], dp, len);
item->ri_buf[item->ri_cnt-1].i_len += len;
item->ri_buf[item->ri_cnt-1].i_addr = ptr;

2
include/linux/mm.h
View File

@ -829,6 +829,8 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags)
return kvmalloc_array(n, size, flags | __GFP_ZERO);
}
extern void *kvrealloc(const void *p, size_t oldsize, size_t newsize,
gfp_t flags);
extern void kvfree(const void *addr);
extern void kvfree_sensitive(const void *addr, size_t len);

15
mm/util.c
View File

@ -635,6 +635,21 @@ void kvfree_sensitive(const void *addr, size_t len)
}
EXPORT_SYMBOL(kvfree_sensitive);
void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
{
void *newp;
if (oldsize >= newsize)
return (void *)p;
newp = kvmalloc(newsize, flags);
if (!newp)
return NULL;
memcpy(newp, p, oldsize);
kvfree(p);
return newp;
}
EXPORT_SYMBOL(kvrealloc);
static inline void *__page_rmapping(struct page *page)
{
unsigned long mapping;