As Hugh said: " The i915 THP splitting inshmem_writepage() was to avoid mm VM_BUG_ONs and crashes when shmem.c did not support huge page swapout: but now you are enabling that support, and such VM_BUG_ONs and crashes are gone (so far as I can see: and this is written on a laptop using the i915 driver). I cannot think of why i915 itself would care how mm implements swapout (beyond enjoying faster): I think all the wbc->split_large_folio you introduce here should be reverted. " So this fixup patch will remove the wbc->split_large_folio as suggested by Hugh. Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> --- This fixup patch is based on 2024-08-28 mm-unstable branch. Andrew, please help to squash this fixup patch. Thanks. --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 1 - include/linux/writeback.h | 1 - mm/shmem.c | 9 ++++----- mm/vmscan.c | 4 +--- 4 files changed, 5 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c index c66cb9c585e1..c5e1c718a6d2 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -308,7 +308,6 @@ void __shmem_writeback(size_t size, struct address_space *mapping) .range_start = 0, .range_end = LLONG_MAX, .for_reclaim = 1, - .split_large_folio = 1, }; unsigned long i; diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 10100e22d5c6..51278327b3c6 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -63,7 +63,6 @@ struct writeback_control { unsigned range_cyclic:1; /* range_start is cyclic */ unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ unsigned unpinned_netfs_wb:1; /* Cleared I_PINNING_NETFS_WB */ - unsigned split_large_folio:1; /* Split large folio for shmem writeback */ /* * When writeback IOs are bounced through async layers, only the diff --git a/mm/shmem.c b/mm/shmem.c index 16099340ca1d..2b0209d6ac9c 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1473,19 +1473,18 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) goto redirty; /* - * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or - * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages, - * and its shmem_writeback() needs them to be split when swapping. + * If CONFIG_THP_SWAP is not enabled, the large folio should be + * split when swapping. * * And shrinkage of pages beyond i_size does not split swap, so * swapout of a large folio crossing i_size needs to split too * (unless fallocate has been used to preallocate beyond EOF). */ if (folio_test_large(folio)) { - split = wbc->split_large_folio; index = shmem_fallocend(inode, DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE)); - if (index > folio->index && index < folio_next_index(folio)) + if ((index > folio->index && index < folio_next_index(folio)) || + !IS_ENABLED(CONFIG_THP_SWAP)) split = true; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 283e3f9d652b..f27792e77a0f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -681,10 +681,8 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping, * not enabled or contiguous swap entries are failed to * allocate. */ - if (shmem_mapping(mapping) && folio_test_large(folio)) { + if (shmem_mapping(mapping) && folio_test_large(folio)) wbc.list = folio_list; - wbc.split_large_folio = !IS_ENABLED(CONFIG_THP_SWAP); - } folio_set_reclaim(folio); res = mapping->a_ops->writepage(&folio->page, &wbc); -- 2.39.3