The patch titled Subject: mm: use memalloc_nofs_save() in page_cache_ra_order() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-use-memalloc_nofs_save-in-page_cache_ra_order.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Kefeng Wang wangkefeng.wang@huawei.com Subject: mm: use memalloc_nofs_save() in page_cache_ra_order() Date: Fri, 26 Apr 2024 19:29:38 +0800

See commit f2c817bed58d ("mm: use memalloc_nofs_save in readahead path"), ensure that page_cache_ra_order() do not attempt to reclaim file-backed pages too, or it leads to a deadlock, found issue when test ext4 large folio.

INFO: task DataXceiver for:7494 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:DataXceiver for state:D stack:0 pid:7494 ppid:1 flags:0x00000200 Call trace: __switch_to+0x14c/0x240 __schedule+0x82c/0xdd0 schedule+0x58/0xf0 io_schedule+0x24/0xa0 __folio_lock+0x130/0x300 migrate_pages_batch+0x378/0x918 migrate_pages+0x350/0x700 compact_zone+0x63c/0xb38 compact_zone_order+0xc0/0x118 try_to_compact_pages+0xb0/0x280 __alloc_pages_direct_compact+0x98/0x248 __alloc_pages+0x510/0x1110 alloc_pages+0x9c/0x130 folio_alloc+0x20/0x78 filemap_alloc_folio+0x8c/0x1b0 page_cache_ra_order+0x174/0x308 ondemand_readahead+0x1c8/0x2b8 page_cache_async_ra+0x68/0xb8 filemap_readahead.isra.0+0x64/0xa8 filemap_get_pages+0x3fc/0x5b0 filemap_splice_read+0xf4/0x280 ext4_file_splice_read+0x2c/0x48 [ext4] vfs_splice_read.part.0+0xa8/0x118 splice_direct_to_actor+0xbc/0x288 do_splice_direct+0x9c/0x108 do_sendfile+0x328/0x468 __arm64_sys_sendfile64+0x8c/0x148 invoke_syscall+0x4c/0x118 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x4c/0x1f8 el0t_64_sync_handler+0xc0/0xc8 el0t_64_sync+0x188/0x190

Link: https://lkml.kernel.org/r/20240426112938.124740-1-wangkefeng.wang@huawei.com Fixes: 793917d997df ("mm/readahead: Add large folio readahead") Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Zhang Yi yi.zhang@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/readahead.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/mm/readahead.c~mm-use-memalloc_nofs_save-in-page_cache_ra_order +++ a/mm/readahead.c @@ -490,6 +490,7 @@ void page_cache_ra_order(struct readahea pgoff_t index = readahead_index(ractl); pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; pgoff_t mark = index + ra->size - ra->async_size; + unsigned int nofs; int err = 0; gfp_t gfp = readahead_gfp_mask(mapping);

@@ -504,6 +505,8 @@ void page_cache_ra_order(struct readahea new_order = min_t(unsigned int, new_order, ilog2(ra->size)); }

+ /* See comment in page_cache_ra_unbounded() */ + nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); while (index <= limit) { unsigned int order = new_order; @@ -527,6 +530,7 @@ void page_cache_ra_order(struct readahea

read_pages(ractl); filemap_invalidate_unlock_shared(mapping); + memalloc_nofs_restore(nofs);

/* * If there were already pages in the page cache, then we may have _

Patches currently in -mm which might be from wangkefeng.wang@huawei.com are

mm-use-memalloc_nofs_save-in-page_cache_ra_order.patch arm64-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch arm-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch mm-move-mm-counter-updating-out-of-set_pte_range.patch mm-filemap-batch-mm-counter-updating-in-filemap_map_pages.patch mm-swapfile-check-usable-swap-device-in-__folio_throttle_swaprate.patch mm-memory-check-userfaultfd_wp-in-vmf_orig_pte_uffd_wp.patch