| Message ID | 1591254347-15912-1-git-send-email-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] iomap: avoid deadlock if memory reclaim is triggered in writepage path | expand |
On Thu, Jun 4, 2020 at 3:06 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > Recently there is a XFS deadlock on our server with an old kernel. > This deadlock is caused by allocating memory in xfs_map_blocks() while > doing writeback on behalf of memroy reclaim. Although this deadlock happens > on an old kernel, I think it could happen on the upstream as well. This > issue only happens once and can't be reproduced, so I haven't tried to > reproduce it on upsteam kernel. > > Bellow is the call trace of this deadlock. > [480594.790087] INFO: task redis-server:16212 blocked for more than 120 seconds. > [480594.790087] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [480594.790088] redis-server D ffffffff8168bd60 0 16212 14347 0x00000004 > [480594.790090] ffff880da128f070 0000000000000082 ffff880f94a2eeb0 ffff880da128ffd8 > [480594.790092] ffff880da128ffd8 ffff880da128ffd8 ffff880f94a2eeb0 ffff88103f9d6c40 > [480594.790094] 0000000000000000 7fffffffffffffff ffff88207ffc0ee8 ffffffff8168bd60 > [480594.790096] Call Trace: > [480594.790101] [<ffffffff8168dce9>] schedule+0x29/0x70 > [480594.790103] [<ffffffff8168b749>] schedule_timeout+0x239/0x2c0 > [480594.790111] [<ffffffff8168d28e>] io_schedule_timeout+0xae/0x130 > [480594.790114] [<ffffffff8168d328>] io_schedule+0x18/0x20 > [480594.790116] [<ffffffff8168bd71>] bit_wait_io+0x11/0x50 > [480594.790118] [<ffffffff8168b895>] __wait_on_bit+0x65/0x90 > [480594.790121] [<ffffffff811814e1>] wait_on_page_bit+0x81/0xa0 > [480594.790125] [<ffffffff81196ad2>] shrink_page_list+0x6d2/0xaf0 > [480594.790130] [<ffffffff811975a3>] shrink_inactive_list+0x223/0x710 > [480594.790135] [<ffffffff81198225>] shrink_lruvec+0x3b5/0x810 > [480594.790139] [<ffffffff8119873a>] shrink_zone+0xba/0x1e0 > [480594.790141] [<ffffffff81198c20>] do_try_to_free_pages+0x100/0x510 > [480594.790143] [<ffffffff8119928d>] try_to_free_mem_cgroup_pages+0xdd/0x170 > [480594.790145] [<ffffffff811f32de>] mem_cgroup_reclaim+0x4e/0x120 > [480594.790147] [<ffffffff811f37cc>] __mem_cgroup_try_charge+0x41c/0x670 > [480594.790153] [<ffffffff811f5cb6>] __memcg_kmem_newpage_charge+0xf6/0x180 > [480594.790157] [<ffffffff8118c72d>] __alloc_pages_nodemask+0x22d/0x420 > [480594.790162] [<ffffffff811d0c7a>] alloc_pages_current+0xaa/0x170 > [480594.790165] [<ffffffff811db8fc>] new_slab+0x30c/0x320 > [480594.790168] [<ffffffff811dd17c>] ___slab_alloc+0x3ac/0x4f0 > [480594.790204] [<ffffffff81685656>] __slab_alloc+0x40/0x5c > [480594.790206] [<ffffffff811dfc43>] kmem_cache_alloc+0x193/0x1e0 > [480594.790233] [<ffffffffa04fab67>] kmem_zone_alloc+0x97/0x130 [xfs] > [480594.790247] [<ffffffffa04f90ba>] _xfs_trans_alloc+0x3a/0xa0 [xfs] > [480594.790261] [<ffffffffa04f915c>] xfs_trans_alloc+0x3c/0x50 [xfs] > [480594.790276] [<ffffffffa04e958b>] xfs_iomap_write_allocate+0x1cb/0x390 [xfs] > [480594.790299] [<ffffffffa04d3616>] xfs_map_blocks+0x1a6/0x210 [xfs] > [480594.790312] [<ffffffffa04d416b>] xfs_do_writepage+0x17b/0x550 [xfs] > [480594.790314] [<ffffffff8118d881>] write_cache_pages+0x251/0x4d0 [xfs] > [480594.790338] [<ffffffffa04d3e05>] xfs_vm_writepages+0xc5/0xe0 [xfs] > [480594.790341] [<ffffffff8118ebfe>] do_writepages+0x1e/0x40 > [480594.790343] [<ffffffff811837b5>] __filemap_fdatawrite_range+0x65/0x80 > [480594.790346] [<ffffffff81183901>] filemap_write_and_wait_range+0x41/0x90 > [480594.790360] [<ffffffffa04df2c6>] xfs_file_fsync+0x66/0x1e0 [xfs] > [480594.790363] [<ffffffff81231cf5>] do_fsync+0x65/0xa0 > [480594.790365] [<ffffffff81231fe3>] SyS_fdatasync+0x13/0x20 > [480594.790367] [<ffffffff81698d09>] system_call_fastpath+0x16/0x1b > > Note that xfs_iomap_write_allocate() is replaced by xfs_convert_blocks() in > commit 4ad765edb02a ("xfs: move xfs_iomap_write_allocate to xfs_aops.c") > and write_cache_pages() is replaced by iomap_writepages() in > commit 598ecfbaa742 ("iomap: lift the xfs writeback code to iomap"). > So for upsteam, the call trace should be, > xfs_vm_writepages > -> iomap_writepages > -> write_cache_pages > -> iomap_do_writepage > -> xfs_map_blocks > -> xfs_convert_blocks > -> xfs_bmapi_convert_delalloc > -> xfs_trans_alloc //It should alloc page with GFP_NOFS > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > --- > v1 - >v2: > - retile the subject from "xfs: avoid deadlock when tigger memory reclam in xfs_map_blocks()" > - set GFP_NOFS in iomap_do_writepage(), per Dave. > --- > fs/iomap/buffered-io.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index a1ed762..f5176e3 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -17,6 +17,7 @@ > #include <linux/bio.h> > #include <linux/sched/signal.h> > #include <linux/migrate.h> > +#include <linux/sched/mm.h> > #include "trace.h" > > #include "../internal.h" > @@ -1478,9 +1479,11 @@ static void iomap_writepage_end_bio(struct bio *bio) > { > struct iomap_writepage_ctx *wpc = data; > struct inode *inode = page->mapping->host; > + unsigned int nofs_flag; > pgoff_t end_index; > u64 end_offset; > loff_t offset; > + int ret; > > trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE); > > @@ -1571,7 +1574,16 @@ static void iomap_writepage_end_bio(struct bio *bio) > end_offset = offset; > } > > - return iomap_writepage_map(wpc, wbc, inode, page, end_offset); > + /* > + * We can allocate memory here while doing writeback on behalf of > + * memory reclaim. To avoid memory allocation deadlocks set the > + * task-wide nofs context for the following operations. > + */ > + nofs_flag = memalloc_nofs_save(); > + ret = iomap_writepage_map(wpc, wbc, inode, page, end_offset); > + memalloc_nofs_restore(nofs_flag); > + > + return ret; > > redirty: > redirty_page_for_writepage(wbc, page); > -- > 1.8.3.1 > Dave, Darrick, Any comments on this version ? Thanks Yafang
On Thu, Jun 04, 2020 at 03:05:47AM -0400, Yafang Shao wrote: > Recently there is a XFS deadlock on our server with an old kernel. > This deadlock is caused by allocating memory in xfs_map_blocks() while > doing writeback on behalf of memroy reclaim. Although this deadlock happens > on an old kernel, I think it could happen on the upstream as well. This > issue only happens once and can't be reproduced, so I haven't tried to > reproduce it on upsteam kernel. The report looks sensible, but I don't think the iomap code is the right place for this. Until/unless the VM people agree that ->writepages(s) generally should not recurse into the fs I think the low-level file system allocating is the right place, so xfs_map_blocks would seem like the correct place.
On Tue, Jun 9, 2020 at 10:03 PM Christoph Hellwig <hch@infradead.org> wrote: > > On Thu, Jun 04, 2020 at 03:05:47AM -0400, Yafang Shao wrote: > > Recently there is a XFS deadlock on our server with an old kernel. > > This deadlock is caused by allocating memory in xfs_map_blocks() while > > doing writeback on behalf of memroy reclaim. Although this deadlock happens > > on an old kernel, I think it could happen on the upstream as well. This > > issue only happens once and can't be reproduced, so I haven't tried to > > reproduce it on upsteam kernel. > > The report looks sensible, but I don't think the iomap code is the > right place for this. Until/unless the VM people agree that > ->writepages(s) generally should not recurse into the fs I think the > low-level file system allocating is the right place, so xfs_map_blocks > would seem like the correct place. Thanks for your comment. That is what I did in the previous version [1]. So should I resend the v1 ? [1]. https://lore.kernel.org/linux-xfs/1591179035-9270-1-git-send-email-laoar.shao@gmail.com/
On Tue, Jun 09, 2020 at 10:28:06PM +0800, Yafang Shao wrote: > On Tue, Jun 9, 2020 at 10:03 PM Christoph Hellwig <hch@infradead.org> wrote: > > > > On Thu, Jun 04, 2020 at 03:05:47AM -0400, Yafang Shao wrote: > > > Recently there is a XFS deadlock on our server with an old kernel. > > > This deadlock is caused by allocating memory in xfs_map_blocks() while > > > doing writeback on behalf of memroy reclaim. Although this deadlock happens > > > on an old kernel, I think it could happen on the upstream as well. This > > > issue only happens once and can't be reproduced, so I haven't tried to > > > reproduce it on upsteam kernel. > > > > The report looks sensible, but I don't think the iomap code is the > > right place for this. Until/unless the VM people agree that > > ->writepages(s) generally should not recurse into the fs I think the > > low-level file system allocating is the right place, so xfs_map_blocks > > would seem like the correct place. > > Thanks for your comment. > That is what I did in the previous version [1]. > So should I resend the v1 ? Well, v1 won't apply. But I do prefer the approach there.
On Tue, Jun 9, 2020 at 10:32 PM Christoph Hellwig <hch@infradead.org> wrote: > > On Tue, Jun 09, 2020 at 10:28:06PM +0800, Yafang Shao wrote: > > On Tue, Jun 9, 2020 at 10:03 PM Christoph Hellwig <hch@infradead.org> wrote: > > > > > > On Thu, Jun 04, 2020 at 03:05:47AM -0400, Yafang Shao wrote: > > > > Recently there is a XFS deadlock on our server with an old kernel. > > > > This deadlock is caused by allocating memory in xfs_map_blocks() while > > > > doing writeback on behalf of memroy reclaim. Although this deadlock happens > > > > on an old kernel, I think it could happen on the upstream as well. This > > > > issue only happens once and can't be reproduced, so I haven't tried to > > > > reproduce it on upsteam kernel. > > > > > > The report looks sensible, but I don't think the iomap code is the > > > right place for this. Until/unless the VM people agree that > > > ->writepages(s) generally should not recurse into the fs I think the > > > low-level file system allocating is the right place, so xfs_map_blocks > > > would seem like the correct place. > > > > Thanks for your comment. > > That is what I did in the previous version [1]. > > So should I resend the v1 ? > > Well, v1 won't apply. But I do prefer the approach there. All right. Let's include MM maintainers and see the opinion from them. Hi Michal, Andrew, What's your opinion on this XFS deadlock ? Should ->writepages(s) generally not recurse into the fs ?
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index a1ed762..f5176e3 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -17,6 +17,7 @@ #include <linux/bio.h> #include <linux/sched/signal.h> #include <linux/migrate.h> +#include <linux/sched/mm.h> #include "trace.h" #include "../internal.h" @@ -1478,9 +1479,11 @@ static void iomap_writepage_end_bio(struct bio *bio) { struct iomap_writepage_ctx *wpc = data; struct inode *inode = page->mapping->host; + unsigned int nofs_flag; pgoff_t end_index; u64 end_offset; loff_t offset; + int ret; trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE); @@ -1571,7 +1574,16 @@ static void iomap_writepage_end_bio(struct bio *bio) end_offset = offset; } - return iomap_writepage_map(wpc, wbc, inode, page, end_offset); + /* + * We can allocate memory here while doing writeback on behalf of + * memory reclaim. To avoid memory allocation deadlocks set the + * task-wide nofs context for the following operations. + */ + nofs_flag = memalloc_nofs_save(); + ret = iomap_writepage_map(wpc, wbc, inode, page, end_offset); + memalloc_nofs_restore(nofs_flag); + + return ret; redirty: redirty_page_for_writepage(wbc, page);
Recently there is a XFS deadlock on our server with an old kernel. This deadlock is caused by allocating memory in xfs_map_blocks() while doing writeback on behalf of memroy reclaim. Although this deadlock happens on an old kernel, I think it could happen on the upstream as well. This issue only happens once and can't be reproduced, so I haven't tried to reproduce it on upsteam kernel. Bellow is the call trace of this deadlock. [480594.790087] INFO: task redis-server:16212 blocked for more than 120 seconds. [480594.790087] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [480594.790088] redis-server D ffffffff8168bd60 0 16212 14347 0x00000004 [480594.790090] ffff880da128f070 0000000000000082 ffff880f94a2eeb0 ffff880da128ffd8 [480594.790092] ffff880da128ffd8 ffff880da128ffd8 ffff880f94a2eeb0 ffff88103f9d6c40 [480594.790094] 0000000000000000 7fffffffffffffff ffff88207ffc0ee8 ffffffff8168bd60 [480594.790096] Call Trace: [480594.790101] [<ffffffff8168dce9>] schedule+0x29/0x70 [480594.790103] [<ffffffff8168b749>] schedule_timeout+0x239/0x2c0 [480594.790111] [<ffffffff8168d28e>] io_schedule_timeout+0xae/0x130 [480594.790114] [<ffffffff8168d328>] io_schedule+0x18/0x20 [480594.790116] [<ffffffff8168bd71>] bit_wait_io+0x11/0x50 [480594.790118] [<ffffffff8168b895>] __wait_on_bit+0x65/0x90 [480594.790121] [<ffffffff811814e1>] wait_on_page_bit+0x81/0xa0 [480594.790125] [<ffffffff81196ad2>] shrink_page_list+0x6d2/0xaf0 [480594.790130] [<ffffffff811975a3>] shrink_inactive_list+0x223/0x710 [480594.790135] [<ffffffff81198225>] shrink_lruvec+0x3b5/0x810 [480594.790139] [<ffffffff8119873a>] shrink_zone+0xba/0x1e0 [480594.790141] [<ffffffff81198c20>] do_try_to_free_pages+0x100/0x510 [480594.790143] [<ffffffff8119928d>] try_to_free_mem_cgroup_pages+0xdd/0x170 [480594.790145] [<ffffffff811f32de>] mem_cgroup_reclaim+0x4e/0x120 [480594.790147] [<ffffffff811f37cc>] __mem_cgroup_try_charge+0x41c/0x670 [480594.790153] [<ffffffff811f5cb6>] __memcg_kmem_newpage_charge+0xf6/0x180 [480594.790157] [<ffffffff8118c72d>] __alloc_pages_nodemask+0x22d/0x420 [480594.790162] [<ffffffff811d0c7a>] alloc_pages_current+0xaa/0x170 [480594.790165] [<ffffffff811db8fc>] new_slab+0x30c/0x320 [480594.790168] [<ffffffff811dd17c>] ___slab_alloc+0x3ac/0x4f0 [480594.790204] [<ffffffff81685656>] __slab_alloc+0x40/0x5c [480594.790206] [<ffffffff811dfc43>] kmem_cache_alloc+0x193/0x1e0 [480594.790233] [<ffffffffa04fab67>] kmem_zone_alloc+0x97/0x130 [xfs] [480594.790247] [<ffffffffa04f90ba>] _xfs_trans_alloc+0x3a/0xa0 [xfs] [480594.790261] [<ffffffffa04f915c>] xfs_trans_alloc+0x3c/0x50 [xfs] [480594.790276] [<ffffffffa04e958b>] xfs_iomap_write_allocate+0x1cb/0x390 [xfs] [480594.790299] [<ffffffffa04d3616>] xfs_map_blocks+0x1a6/0x210 [xfs] [480594.790312] [<ffffffffa04d416b>] xfs_do_writepage+0x17b/0x550 [xfs] [480594.790314] [<ffffffff8118d881>] write_cache_pages+0x251/0x4d0 [xfs] [480594.790338] [<ffffffffa04d3e05>] xfs_vm_writepages+0xc5/0xe0 [xfs] [480594.790341] [<ffffffff8118ebfe>] do_writepages+0x1e/0x40 [480594.790343] [<ffffffff811837b5>] __filemap_fdatawrite_range+0x65/0x80 [480594.790346] [<ffffffff81183901>] filemap_write_and_wait_range+0x41/0x90 [480594.790360] [<ffffffffa04df2c6>] xfs_file_fsync+0x66/0x1e0 [xfs] [480594.790363] [<ffffffff81231cf5>] do_fsync+0x65/0xa0 [480594.790365] [<ffffffff81231fe3>] SyS_fdatasync+0x13/0x20 [480594.790367] [<ffffffff81698d09>] system_call_fastpath+0x16/0x1b Note that xfs_iomap_write_allocate() is replaced by xfs_convert_blocks() in commit 4ad765edb02a ("xfs: move xfs_iomap_write_allocate to xfs_aops.c") and write_cache_pages() is replaced by iomap_writepages() in commit 598ecfbaa742 ("iomap: lift the xfs writeback code to iomap"). So for upsteam, the call trace should be, xfs_vm_writepages -> iomap_writepages -> write_cache_pages -> iomap_do_writepage -> xfs_map_blocks -> xfs_convert_blocks -> xfs_bmapi_convert_delalloc -> xfs_trans_alloc //It should alloc page with GFP_NOFS Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- v1 - >v2: - retile the subject from "xfs: avoid deadlock when tigger memory reclam in xfs_map_blocks()" - set GFP_NOFS in iomap_do_writepage(), per Dave. --- fs/iomap/buffered-io.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)