| Message ID | 20210625023029.1472466-2-david@fromorbit.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm, xfs: memory allocation improvements | expand |
On 2021/6/25 10:30, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > 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: 771915c4f688 ("xfs: remove kmem_realloc()") > Signed-off-by: Dave Chinner <dchinner@redhat.com> Thank you for your patch. > --- > fs/xfs/xfs_log_recover.c | 2 +- > include/linux/mm.h | 14 ++++++++++++++ > 2 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c > index 1721fce2ec94..fee4fbadea0a 100644 > --- a/fs/xfs/xfs_log_recover.c > +++ b/fs/xfs/xfs_log_recover.c > @@ -2062,7 +2062,7 @@ 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); > 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; > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8ae31622deef..34d88ff00f31 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -830,6 +830,20 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) > extern void kvfree(const void *addr); > extern void kvfree_sensitive(const void *addr, size_t len); > > +static inline void *kvrealloc(void *p, size_t oldsize, size_t newsize, > + gfp_t flags) > +{ > + void *newp; > + > + if (oldsize >= newsize) > + return p; > + newp = kvmalloc(newsize, flags); Shouldn't we check newp against NULL before memcpy? Thanks. > + memcpy(newp, p, oldsize); > + kvfree(p); > + return newp; > +} > + > + > static inline int head_compound_mapcount(struct page *head) > { > return atomic_read(compound_mapcount_ptr(head)) + 1; >
On Fri, Jun 25, 2021 at 12:30:27PM +1000, Dave Chinner wrote: > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8ae31622deef..34d88ff00f31 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -830,6 +830,20 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) > extern void kvfree(const void *addr); > extern void kvfree_sensitive(const void *addr, size_t len); > > +static inline void *kvrealloc(void *p, size_t oldsize, size_t newsize, > + gfp_t flags) > +{ > + void *newp; > + > + if (oldsize >= newsize) > + return p; > + newp = kvmalloc(newsize, flags); > + memcpy(newp, p, oldsize); > + kvfree(p); > + return newp; > +} Why make this an inline function instead of putting it in mm/util.c?
On Fri, Jun 25, 2021 at 04:54:11AM +0100, Matthew Wilcox wrote: > On Fri, Jun 25, 2021 at 12:30:27PM +1000, Dave Chinner wrote: > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 8ae31622deef..34d88ff00f31 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -830,6 +830,20 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) > > extern void kvfree(const void *addr); > > extern void kvfree_sensitive(const void *addr, size_t len); > > > > +static inline void *kvrealloc(void *p, size_t oldsize, size_t newsize, > > + gfp_t flags) > > +{ > > + void *newp; > > + > > + if (oldsize >= newsize) > > + return p; > > + newp = kvmalloc(newsize, flags); > > + memcpy(newp, p, oldsize); > > + kvfree(p); > > + return newp; > > +} > > Why make this an inline function instead of putting it in mm/util.c? Not fussed, I can do that. Cheers, Dave.
On Fri, Jun 25, 2021 at 10:40:08AM +0800, Miaohe Lin wrote: > On 2021/6/25 10:30, Dave Chinner wrote: > > @@ -830,6 +830,20 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) > > extern void kvfree(const void *addr); > > extern void kvfree_sensitive(const void *addr, size_t len); > > > > +static inline void *kvrealloc(void *p, size_t oldsize, size_t newsize, > > + gfp_t flags) > > +{ > > + void *newp; > > + > > + if (oldsize >= newsize) > > + return p; > > + newp = kvmalloc(newsize, flags); > > Shouldn't we check newp against NULL before memcpy? Sure, the flags cwwe pass it from XFS mean it can't fail, but I guess someone could add a noretry flag or something like that... Cheers, Dave.
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index 1721fce2ec94..fee4fbadea0a 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -2062,7 +2062,7 @@ 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); 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; diff --git a/include/linux/mm.h b/include/linux/mm.h index 8ae31622deef..34d88ff00f31 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -830,6 +830,20 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) extern void kvfree(const void *addr); extern void kvfree_sensitive(const void *addr, size_t len); +static inline void *kvrealloc(void *p, size_t oldsize, size_t newsize, + gfp_t flags) +{ + void *newp; + + if (oldsize >= newsize) + return p; + newp = kvmalloc(newsize, flags); + memcpy(newp, p, oldsize); + kvfree(p); + return newp; +} + + static inline int head_compound_mapcount(struct page *head) { return atomic_read(compound_mapcount_ptr(head)) + 1;