January 2025 - Linux-stable-mirror

[PATCH v4 04/10] btrfs: do proper folio cleanup when cow_file_range() failed

by Qu Wenruo

[BUG] When testing with COW fixup marked as BUG_ON() (this is involved with the new pin_user_pages*() change, which should not result new out-of-band dirty pages), I hit a crash triggered by the BUG_ON() from hitting COW fixup path. This BUG_ON() happens just after a failed btrfs_run_delalloc_range(): BTRFS error (device dm-2): failed to run delalloc range, root 348 ino 405 folio 65536 submit_bitmap 6-15 start 90112 len 106496: -28 ------------[ cut here ]------------ kernel BUG at fs/btrfs/extent_io.c:1444! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP CPU: 0 UID: 0 PID: 434621 Comm: kworker/u24:8 Tainted: G OE 6.12.0-rc7-custom+ #86 Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs] pc : extent_writepage_io+0x2d4/0x308 [btrfs] lr : extent_writepage_io+0x2d4/0x308 [btrfs] Call trace: extent_writepage_io+0x2d4/0x308 [btrfs] extent_writepage+0x218/0x330 [btrfs] extent_write_cache_pages+0x1d4/0x4b0 [btrfs] btrfs_writepages+0x94/0x150 [btrfs] do_writepages+0x74/0x190 filemap_fdatawrite_wbc+0x88/0xc8 start_delalloc_inodes+0x180/0x3b0 [btrfs] btrfs_start_delalloc_roots+0x174/0x280 [btrfs] shrink_delalloc+0x114/0x280 [btrfs] flush_space+0x250/0x2f8 [btrfs] btrfs_async_reclaim_data_space+0x180/0x228 [btrfs] process_one_work+0x164/0x408 worker_thread+0x25c/0x388 kthread+0x100/0x118 ret_from_fork+0x10/0x20 Code: aa1403e1 9402f3ef aa1403e0 9402f36f (d4210000) ---[ end trace 0000000000000000 ]--- [CAUSE] That failure is mostly from cow_file_range(), where we can hit -ENOSPC. Although the -ENOSPC is already a bug related to our space reservation code, let's just focus on the error handling. For example, we have the following dirty range [0, 64K) of an inode, with 4K sector size and 4K page size: 0 16K 32K 48K 64K |///////////////////////////////////////| |#######################################| Where |///| means page are still dirty, and |###| means the extent io tree has EXTENT_DELALLOC flag. - Enter extent_writepage() for page 0 - Enter btrfs_run_delalloc_range() for range [0, 64K) - Enter cow_file_range() for range [0, 64K) - Function btrfs_reserve_extent() only reserved one 16K extent So we created extent map and ordered extent for range [0, 16K) 0 16K 32K 48K 64K |////////|//////////////////////////////| |<- OE ->|##############################| And range [0, 16K) has its delalloc flag cleared. But since we haven't yet submit any bio, involved 4 pages are still dirty. - Function btrfs_reserve_extent() return with -ENOSPC Now we have to run error cleanup, which will clear all EXTENT_DELALLOC* flags and clear the dirty flags for the remaining ranges: 0 16K 32K 48K 64K |////////| | | | | Note that range [0, 16K) still has their pages dirty. - Some time later, writeback are triggered again for the range [0, 16K) since the page range still have dirty flags. - btrfs_run_delalloc_range() will do nothing because there is no EXTENT_DELALLOC flag. - extent_writepage_io() find page 0 has no ordered flag Which falls into the COW fixup path, triggering the BUG_ON(). Unfortunately this error handling bug dates back to the introduction of btrfs. Thankfully with the abuse of cow fixup, at least it won't crash the kernel. [FIX] Instead of immediately unlock the extent and folios, we keep the extent and folios locked until either erroring out or the whole delalloc range finished. When the whole delalloc range finished without error, we just unlock the whole range with PAGE_SET_ORDERED (and PAGE_UNLOCK for !keep_locked cases), with EXTENT_DELALLOC and EXTENT_LOCKED cleared. And those involved folios will be properly submitted, with their dirty flags cleared during submission. For the error path, it will be a little more complex: - The range with ordered extent allocated (range (1)) We only clear the EXTENT_DELALLOC and EXTENT_LOCKED, as the remaining flags are cleaned up by btrfs_mark_ordered_io_finished()->btrfs_finish_one_ordered(). For folios we finish the IO (clear dirty, start writeback and immediately finish the writeback) and unlock the folios. - The range with reserved extent but no ordered extent (range(2)) - The range we never touched (range(3)) For both range (2) and range(3) the behavior is not changed. Now even if cow_file_range() failed halfway with some successfully reserved extents/ordered extents, we will keep all folios clean, so there will be no future writeback triggered on them. Cc: stable(a)vger.kernel.org Reviewed-by: Boris Burkov <boris(a)bur.io> Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/inode.c | 65 ++++++++++++++++++++++++------------------------ 1 file changed, 32 insertions(+), 33 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c23993cb7bdc..b94c4abcda3a 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1363,6 +1363,17 @@ static noinline int cow_file_range(struct btrfs_inode *inode, alloc_hint = btrfs_get_extent_allocation_hint(inode, start, num_bytes); + /* + * We're not doing compressed IO, don't unlock the first page + * (which the caller expects to stay locked), don't clear any + * dirty bits and don't set any writeback bits + * + * Do set the Ordered (Private2) bit so we know this page was + * properly setup for writepage. + */ + page_ops = (keep_locked ? 0 : PAGE_UNLOCK); + page_ops |= PAGE_SET_ORDERED; + /* * Relocation relies on the relocated extents to have exactly the same * size as the original extents. Normally writeback for relocation data @@ -1422,6 +1433,10 @@ static noinline int cow_file_range(struct btrfs_inode *inode, file_extent.offset = 0; file_extent.compression = BTRFS_COMPRESS_NONE; + /* + * Locked range will be released either during error clean up or + * after the whole range is finished. + */ lock_extent(&inode->io_tree, start, start + cur_alloc_size - 1, &cached); @@ -1467,21 +1482,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode, btrfs_dec_block_group_reservations(fs_info, ins.objectid); - /* - * We're not doing compressed IO, don't unlock the first page - * (which the caller expects to stay locked), don't clear any - * dirty bits and don't set any writeback bits - * - * Do set the Ordered flag so we know this page was - * properly setup for writepage. - */ - page_ops = (keep_locked ? 0 : PAGE_UNLOCK); - page_ops |= PAGE_SET_ORDERED; - - extent_clear_unlock_delalloc(inode, start, start + cur_alloc_size - 1, - locked_folio, &cached, - EXTENT_LOCKED | EXTENT_DELALLOC, - page_ops); if (num_bytes < cur_alloc_size) num_bytes = 0; else @@ -1498,6 +1498,9 @@ static noinline int cow_file_range(struct btrfs_inode *inode, if (ret) goto out_unlock; } + extent_clear_unlock_delalloc(inode, orig_start, end, locked_folio, &cached, + EXTENT_LOCKED | EXTENT_DELALLOC, + page_ops); done: if (done_offset) *done_offset = end; @@ -1518,35 +1521,31 @@ static noinline int cow_file_range(struct btrfs_inode *inode, * We process each region below. */ - clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW | - EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV; - page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK; - /* * For the range (1). We have already instantiated the ordered extents * for this region. They are cleaned up by * btrfs_cleanup_ordered_extents() in e.g, - * btrfs_run_delalloc_range(). EXTENT_LOCKED | EXTENT_DELALLOC are - * already cleared in the above loop. And, EXTENT_DELALLOC_NEW | - * EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV are handled by the cleanup - * function. + * btrfs_run_delalloc_range(). + * EXTENT_DELALLOC_NEW | EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV + * are also handled by the cleanup function. * - * However, in case of @keep_locked, we still need to unlock the pages - * (except @locked_folio) to ensure all the pages are unlocked. + * So here we only clear EXTENT_LOCKED and EXTENT_DELALLOC flag, + * and finish the writeback of the involved folios, which will be + * never submitted. */ - if (keep_locked && orig_start < start) { + if (orig_start < start) { + clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC; + page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK; + if (!locked_folio) mapping_set_error(inode->vfs_inode.i_mapping, ret); extent_clear_unlock_delalloc(inode, orig_start, start - 1, - locked_folio, NULL, 0, page_ops); + locked_folio, NULL, clear_bits, page_ops); } - /* - * At this point we're unlocked, we want to make sure we're only - * clearing these flags under the extent lock, so lock the rest of the - * range and clear everything up. - */ - lock_extent(&inode->io_tree, start, end, NULL); + clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW | + EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV; + page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK; /* * For the range (2). If we reserved an extent for our delalloc range -- 2.47.1

3 months, 1 week

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[PATCH v4 02/10] btrfs: fix double accounting race when extent_writepage_io() failed

by Qu Wenruo

[BUG] If submit_one_sector() failed inside extent_writepage_io() for sector size < page size cases (e.g. 4K sector size and 64K page size), then we can hit double ordered extent accounting error. This should be very rare, as submit_one_sector() only fails when we failed to grab the extent map, and such extent map should exist inside the memory and have been pinned. [CAUSE] For example we have the following folio layout: 0 4K 32K 48K 60K 64K |//| |//////| |///| Where |///| is the dirty range we need to writeback. The 3 different dirty ranges are submitted for regular COW. Now we hit the following sequence: - submit_one_sector() returned 0 for [0, 4K) - submit_one_sector() returned 0 for [32K, 48K) - submit_one_sector() returned error for [60K, 64K) - btrfs_mark_ordered_io_finished() called for the whole folio This will mark the following ranges as finished: * [0, 4K) * [32K, 48K) Both ranges have their IO already submitted, this cleanup will lead to double accounting. * [60K, 64K) That's the correct cleanup. The only good news is, this error is only theoretical, as the target extent map is always pinned, thus we should directly grab it from memory, other than reading it from the disk. [FIX] Instead of calling btrfs_mark_ordered_io_finished() for the whole folio range, which can touch ranges we should not touch, instead move the error handling inside extent_writepage_io(). So that we can cleanup exact sectors that are ought to be submitted but failed. This provide much more accurate cleanup, avoiding the double accounting. Cc: stable(a)vger.kernel.org # 5.15+ Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/extent_io.c | 37 ++++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 7aa3d8c2b0c3..f50e4fccd909 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1420,6 +1420,7 @@ static noinline_for_stack int extent_writepage_io(struct btrfs_inode *inode, struct btrfs_fs_info *fs_info = inode->root->fs_info; unsigned long range_bitmap = 0; bool submitted_io = false; + bool error = false; const u64 folio_start = folio_pos(folio); u64 cur; int bit; @@ -1462,11 +1463,26 @@ static noinline_for_stack int extent_writepage_io(struct btrfs_inode *inode, break; } ret = submit_one_sector(inode, folio, cur, bio_ctrl, i_size); - if (ret < 0) - goto out; + if (unlikely(ret < 0)) { + /* + * bio_ctrl may contain a bio crossing several folios. + * Submit it immediately so that the bio has a chance + * to finish normally, other than marked as error. + */ + submit_one_bio(bio_ctrl); + /* + * Failed to grab the extent map which should be very rare. + * Since there is no bio submitted to finish the ordered + * extent, we have to manually finish this sector. + */ + btrfs_mark_ordered_io_finished(inode, folio, cur, + fs_info->sectorsize, false); + error = true; + continue; + } submitted_io = true; } -out: + /* * If we didn't submitted any sector (>= i_size), folio dirty get * cleared but PAGECACHE_TAG_DIRTY is not cleared (only cleared @@ -1474,8 +1490,11 @@ static noinline_for_stack int extent_writepage_io(struct btrfs_inode *inode, * * Here we set writeback and clear for the range. If the full folio * is no longer dirty then we clear the PAGECACHE_TAG_DIRTY tag. + * + * If we hit any error, the corresponding sector will still be dirty + * thus no need to clear PAGECACHE_TAG_DIRTY. */ - if (!submitted_io) { + if (!submitted_io && !error) { btrfs_folio_set_writeback(fs_info, folio, start, len); btrfs_folio_clear_writeback(fs_info, folio, start, len); } @@ -1495,7 +1514,6 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl { struct btrfs_inode *inode = BTRFS_I(folio->mapping->host); struct btrfs_fs_info *fs_info = inode->root->fs_info; - const u64 page_start = folio_pos(folio); int ret; size_t pg_offset; loff_t i_size = i_size_read(&inode->vfs_inode); @@ -1538,10 +1556,6 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl bio_ctrl->wbc->nr_to_write--; - if (ret) - btrfs_mark_ordered_io_finished(inode, folio, - page_start, PAGE_SIZE, !ret); - done: if (ret < 0) mapping_set_error(folio->mapping, ret); @@ -2314,11 +2328,8 @@ void extent_write_locked_range(struct inode *inode, const struct folio *locked_f if (ret == 1) goto next_page; - if (ret) { - btrfs_mark_ordered_io_finished(BTRFS_I(inode), folio, - cur, cur_len, !ret); + if (ret) mapping_set_error(mapping, ret); - } btrfs_folio_end_lock(fs_info, folio, cur, cur_len); if (ret < 0) found_error = true; -- 2.47.1

3 months, 1 week

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[PATCH v4 01/10] btrfs: fix double accounting race when btrfs_run_delalloc_range() failed

by Qu Wenruo

[BUG] When running btrfs with block size (4K) smaller than page size (64K, aarch64), there is a very high chance to crash the kernel at generic/750, with the following messages: (before the call traces, there are 3 extra debug messages added) BTRFS warning (device dm-3): read-write for sector size 4096 with page size 65536 is experimental BTRFS info (device dm-3): checking UUID tree hrtimer: interrupt took 5451385 ns BTRFS error (device dm-3): cow_file_range failed, root=4957 inode=257 start=1605632 len=69632: -28 BTRFS error (device dm-3): run_delalloc_nocow failed, root=4957 inode=257 start=1605632 len=69632: -28 BTRFS error (device dm-3): failed to run delalloc range, root=4957 ino=257 folio=1572864 submit_bitmap=8-15 start=1605632 len=69632: -28 ------------[ cut here ]------------ WARNING: CPU: 2 PID: 3020984 at ordered-data.c:360 can_finish_ordered_extent+0x370/0x3b8 [btrfs] CPU: 2 UID: 0 PID: 3020984 Comm: kworker/u24:1 Tainted: G OE 6.13.0-rc1-custom+ #89 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs] pc : can_finish_ordered_extent+0x370/0x3b8 [btrfs] lr : can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] Call trace: can_finish_ordered_extent+0x370/0x3b8 [btrfs] (P) can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] (L) btrfs_mark_ordered_io_finished+0x130/0x2b8 [btrfs] extent_writepage+0x10c/0x3b8 [btrfs] extent_write_cache_pages+0x21c/0x4e8 [btrfs] btrfs_writepages+0x94/0x160 [btrfs] do_writepages+0x74/0x190 filemap_fdatawrite_wbc+0x74/0xa0 start_delalloc_inodes+0x17c/0x3b0 [btrfs] btrfs_start_delalloc_roots+0x17c/0x288 [btrfs] shrink_delalloc+0x11c/0x280 [btrfs] flush_space+0x288/0x328 [btrfs] btrfs_async_reclaim_data_space+0x180/0x228 [btrfs] process_one_work+0x228/0x680 worker_thread+0x1bc/0x360 kthread+0x100/0x118 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1605632 OE len=16384 to_dec=16384 left=0 BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1622016 OE len=12288 to_dec=12288 left=0 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1634304 OE len=8192 to_dec=4096 left=0 CPU: 1 UID: 0 PID: 3286940 Comm: kworker/u24:3 Tainted: G W OE 6.13.0-rc1-custom+ #89 Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: btrfs_work_helper [btrfs] (btrfs-endio-write) pstate: 404000c5 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : process_one_work+0x110/0x680 lr : worker_thread+0x1bc/0x360 Call trace: process_one_work+0x110/0x680 (P) worker_thread+0x1bc/0x360 (L) worker_thread+0x1bc/0x360 kthread+0x100/0x118 ret_from_fork+0x10/0x20 Code: f84086a1 f9000fe1 53041c21 b9003361 (f9400661) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Oops: Fatal exception SMP: stopping secondary CPUs SMP: failed to stop secondary CPUs 2-3 Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: 0x275bb9540000 from 0xffff800080000000 PHYS_OFFSET: 0xffff8fbba0000000 CPU features: 0x100,00000070,00801250,8201720b [CAUSE] The above warning is triggered immediately after the delalloc range failure, this happens in the following sequence: - Range [1568K, 1636K) is dirty 1536K 1568K 1600K 1636K 1664K | |/////////|////////| | Where 1536K, 1600K and 1664K are page boundaries (64K page size) - Enter extent_writepage() for page 1536K - Enter run_delalloc_nocow() with locked page 1536K and range [1568K, 1636K) This is due to the inode has preallocated extents. - Enter cow_file_range() with locked page 1536K and range [1568K, 1636K) - btrfs_reserve_extent() only reserved two extents The main loop of cow_file_range() only reserved two data extents, Now we have: 1536K 1568K 1600K 1636K 1664K | |<-->|<--->|/|///////| | 1584K 1596K Range [1568K, 1596K) has ordered extent reserved. - btrfs_reserve_extent() failed inside cow_file_range() for file offset 1596K This is already a bug in our space reservation code, but for now let's focus on the error handling path. Now cow_file_range() returned -ENOSPC. - btrfs_run_delalloc_range() do error cleanup <<< ROOT CAUSE Call btrfs_cleanup_ordered_extents() with locked folio 1536K and range [1568K, 1636K) Function btrfs_cleanup_ordered_extents() normally needs to skip the ranges inside the folio, as it will normally be cleaned up by extent_writepage(). Such split error handling is already problematic in the first place. What's worse is the folio range skipping itself, which is not taking subpage cases into consideration at all, it will only skip the range if the page start >= the range start. In our case, the page start < the range start, since for subpage cases we can have delalloc ranges inside the folio but not covering the folio. So it doesn't skip the page range at all. This means all the ordered extents, both [1568K, 1584K) and [1584K, 1596K) will be marked as IOERR. And those two ordered extents have no more pending ios, it is marked finished, and *QUEUED* to be deleted from the io tree. - extent_writepage() do error cleanup Call btrfs_mark_ordered_io_finished() for the range [1536K, 1600K). Although ranges [1568K, 1584K) and [1584K, 1596K) are finished, the deletion from io tree is async, it may or may not happen at this timing. If the ranges are not yet removed, we will do double cleaning on those ranges, triggers the above ordered extent warnings. In theory there are other bugs, like the cleanup in extent_writepage() can cause double accounting on ranges that are submitted async (compression for example). But that's much harder to trigger because normally we do not mix regular and compression delalloc ranges. [FIX] The folio range split is already buggy and not subpage compatible, it's introduced a long time ago where subpage support is not even considered. So instead of splitting the ordered extents cleanup into the folio range and out of folio range, do all the cleanup inside writepage_delalloc(). - Pass @NULL as locked_folio for btrfs_cleanup_ordered_extents() in btrfs_run_delalloc_range() - Skip the btrfs_cleanup_ordered_extents() if writepage_delalloc() failed So all ordered extents are only cleaned up by btrfs_run_delalloc_range(). - Handle the ranges that already have ordered extents allocated If part of the folio already has ordered extent allocated, and btrfs_run_delalloc_range() failed, we also need to cleanup that range. Now we have a concentrated error handling for ordered extents during btrfs_run_delalloc_range(). Cc: stable(a)vger.kernel.org # 5.15+ Fixes: d1051d6ebf8e ("btrfs: Fix error handling in btrfs_cleanup_ordered_extents") Reviewed-by: Boris Burkov <boris(a)bur.io> Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/extent_io.c | 57 ++++++++++++++++++++++++++++++++++++-------- fs/btrfs/inode.c | 2 +- 2 files changed, 48 insertions(+), 11 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index c068a442753c..7aa3d8c2b0c3 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1136,12 +1136,17 @@ static bool find_next_delalloc_bitmap(struct folio *folio, /* * helper for extent_writepage(), doing all of the delayed allocation setup. * - * This returns 1 if btrfs_run_delalloc_range function did all the work required - * to write the page (copy into inline extent). In this case the IO has - * been started and the page is already unlocked. + * Return >0 if all the dirty blocks are submitted async (compression) or inlined. + * The @folio should no longer be touched (treat it as already unlocked). * - * This returns 0 if all went well (page still locked) - * This returns < 0 if there were errors (page still locked) + * Return 0 if there is still dirty block that needs to be submitted through + * extent_writepage_io(). + * bio_ctrl->submit_bitmap will indicate which blocks of the folio should be + * submitted, and @folio is still kept locked. + * + * Return <0 if there is any error hit. + * Any allocated ordered extent range covering this folio will be marked + * finished (IOERR), and @folio is still kept locked. */ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, struct folio *folio, @@ -1159,6 +1164,16 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, * last delalloc end. */ u64 last_delalloc_end = 0; + /* + * The range end (exclusive) of the last successfully finished delalloc + * range. + * Any range covered by ordered extent must either be manually marked + * finished (error handling), or has IO submitted (and finish the + * ordered extent normally). + * + * This records the end of ordered extent cleanup if we hit an error. + */ + u64 last_finished_delalloc_end = page_start; u64 delalloc_start = page_start; u64 delalloc_end = page_end; u64 delalloc_to_write = 0; @@ -1227,11 +1242,19 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, found_len = last_delalloc_end + 1 - found_start; if (ret >= 0) { + /* + * Some delalloc range may be created by previous folios. + * Thus we still need to clean those range up during error + * handling. + */ + last_finished_delalloc_end = found_start; /* No errors hit so far, run the current delalloc range. */ ret = btrfs_run_delalloc_range(inode, folio, found_start, found_start + found_len - 1, wbc); + if (ret >= 0) + last_finished_delalloc_end = found_start + found_len; } else { /* * We've hit an error during previous delalloc range, @@ -1266,8 +1289,22 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, delalloc_start = found_start + found_len; } - if (ret < 0) + /* + * It's possible we have some ordered extents created before we hit + * an error, cleanup non-async successfully created delalloc ranges. + */ + if (unlikely(ret < 0)) { + unsigned int bitmap_size = min( + (last_finished_delalloc_end - page_start) >> + fs_info->sectorsize_bits, + fs_info->sectors_per_page); + + for_each_set_bit(bit, &bio_ctrl->submit_bitmap, bitmap_size) + btrfs_mark_ordered_io_finished(inode, folio, + page_start + (bit << fs_info->sectorsize_bits), + fs_info->sectorsize, false); return ret; + } out: if (last_delalloc_end) delalloc_end = last_delalloc_end; @@ -1501,13 +1538,13 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl bio_ctrl->wbc->nr_to_write--; -done: - if (ret) { + if (ret) btrfs_mark_ordered_io_finished(inode, folio, page_start, PAGE_SIZE, !ret); - mapping_set_error(folio->mapping, ret); - } +done: + if (ret < 0) + mapping_set_error(folio->mapping, ret); /* * Only unlock ranges that are submitted. As there can be some async * submitted ranges inside the folio. diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1546f341f9a4..85e36dbe1e1f 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2301,7 +2301,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct folio *locked_fol out: if (ret < 0) - btrfs_cleanup_ordered_extents(inode, locked_folio, start, + btrfs_cleanup_ordered_extents(inode, NULL, start, end - start + 1); return ret; } -- 2.47.1

3 months, 1 week

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[PATCH] tty: xilinx_uartps: split sysrq handling

by Sean Anderson

lockdep detects the following circular locking dependency: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. However, if (as shown above) cdns_uart_console_write runs before port->sysrq is set, then it will try to take the port lock anyway. This may result in a deadlock. Fix this by splitting sysrq handling into two parts. We use the prepare helper under the port lock and defer handling until we release the lock. Fixes: 74ea66d4ca06 ("tty: xuartps: Improve sysrq handling") Signed-off-by: Sean Anderson <sean.anderson(a)linux.dev> Cc: <stable(a)vger.kernel.org> # c980248179d: serial: xilinx_uartps: Use port lock wrappers --- drivers/tty/serial/xilinx_uartps.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index beb151be4d32..92ec51870d1d 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -287,7 +287,7 @@ static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus) continue; } - if (uart_handle_sysrq_char(port, data)) + if (uart_prepare_sysrq_char(port, data)) continue; if (is_rxbs_support) { @@ -495,7 +495,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id) !(readl(port->membase + CDNS_UART_CR) & CDNS_UART_CR_RX_DIS)) cdns_uart_handle_rx(dev_id, isrstatus); - uart_port_unlock(port); + uart_unlock_and_check_sysrq(port); return IRQ_HANDLED; } @@ -1380,9 +1380,7 @@ static void cdns_uart_console_write(struct console *co, const char *s, unsigned int imr, ctrl; int locked = 1; - if (port->sysrq) - locked = 0; - else if (oops_in_progress) + if (oops_in_progress) locked = uart_port_trylock_irqsave(port, &flags); else uart_port_lock_irqsave(port, &flags); -- 2.35.1.1320.gc452695387.dirty

3 months, 1 week

2
1
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[PATCH] KVM: PPC: Enable CAP_SPAPR_TCE_VFIO on pSeries KVM guests

by Amit Machhiwal

Currently, on book3s-hv, the capability KVM_CAP_SPAPR_TCE_VFIO is only available for KVM Guests running on PowerNV and not for the KVM guests running on pSeries hypervisors. This prevents a pSeries hypervisor from leveraging the in-kernel acceleration for H_PUT_TCE_INDIRECT and H_STUFF_TCE hcalls that results in slow startup times for large memory guests. Fix this by enabling the CAP_SPAPR_TCE_VFIO on the pSeries hosts for the nested PAPR guests. Fixes: f431a8cde7f1 ("powerpc/iommu: Reimplement the iommu_table_group_ops for pSeries") Cc: stable(a)vger.kernel.org Signed-off-by: Amit Machhiwal <amachhiw(a)linux.ibm.com> --- arch/powerpc/kvm/powerpc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index ce1d91eed231..9c479c7381e4 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -554,7 +554,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = 1; break; case KVM_CAP_SPAPR_TCE_VFIO: - r = !!cpu_has_feature(CPU_FTR_HVMODE); + r = !!cpu_has_feature(CPU_FTR_HVMODE) || is_kvmppc_hv_enabled(kvm); break; case KVM_CAP_PPC_RTAS: case KVM_CAP_PPC_FIXUP_HCALL: base-commit: eea6e4b4dfb8859446177c32961c96726d0117be -- 2.47.1

3 months, 1 week

2
1
0 0

[PATCH net] net: mana: Cleanup "mana" debugfs dir after cleanup of all children

by Shradha Gupta

In mana_driver_exit(), mana_debugfs_root gets cleanup before any of it's children (which happens later in the pci_unregister_driver()). Due to this, when mana driver is configured as a module and rmmod is invoked, following stack gets printed along with failure in rmmod command. [ 2399.317651] BUG: kernel NULL pointer dereference, address: 0000000000000098 [ 2399.318657] #PF: supervisor write access in kernel mode [ 2399.319057] #PF: error_code(0x0002) - not-present page [ 2399.319528] PGD 10eb68067 P4D 0 [ 2399.319914] Oops: Oops: 0002 [#1] SMP NOPTI [ 2399.320308] CPU: 72 UID: 0 PID: 5815 Comm: rmmod Not tainted 6.13.0-rc5+ #89 [ 2399.320986] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 09/28/2024 [ 2399.321892] RIP: 0010:down_write+0x1a/0x50 [ 2399.322303] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 54 49 89 fc e8 9d cd ff ff 31 c0 ba 01 00 00 00 <f0> 49 0f b1 14 24 75 17 65 48 8b 05 f6 84 dd 5f 49 89 44 24 08 4c [ 2399.323669] RSP: 0018:ff53859d6c663a70 EFLAGS: 00010246 [ 2399.324061] RAX: 0000000000000000 RBX: ff1d4eb505060180 RCX: ffffff8100000000 [ 2399.324620] RDX: 0000000000000001 RSI: 0000000000000064 RDI: 0000000000000098 [ 2399.325167] RBP: ff53859d6c663a78 R08: 00000000000009c4 R09: ff1d4eb4fac90000 [ 2399.325681] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000098 [ 2399.326185] R13: ff1d4e42e1a4a0c8 R14: ff1d4eb538ce0000 R15: 0000000000000098 [ 2399.326755] FS: 00007fe729570000(0000) GS:ff1d4eb2b7200000(0000) knlGS:0000000000000000 [ 2399.327269] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2399.327690] CR2: 0000000000000098 CR3: 00000001c0584005 CR4: 0000000000373ef0 [ 2399.328166] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 2399.328623] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [ 2399.329055] Call Trace: [ 2399.329243] <TASK> [ 2399.329379] ? show_regs+0x69/0x80 [ 2399.329602] ? __die+0x25/0x70 [ 2399.329856] ? page_fault_oops+0x271/0x550 [ 2399.330088] ? psi_group_change+0x217/0x470 [ 2399.330341] ? do_user_addr_fault+0x455/0x7b0 [ 2399.330667] ? finish_task_switch.isra.0+0x91/0x2f0 [ 2399.331004] ? exc_page_fault+0x73/0x160 [ 2399.331275] ? asm_exc_page_fault+0x27/0x30 [ 2399.343324] ? down_write+0x1a/0x50 [ 2399.343631] simple_recursive_removal+0x4d/0x2c0 [ 2399.343977] ? __pfx_remove_one+0x10/0x10 [ 2399.344251] debugfs_remove+0x45/0x70 [ 2399.344511] mana_destroy_rxq+0x44/0x400 [mana] [ 2399.344845] mana_destroy_vport+0x54/0x1c0 [mana] [ 2399.345229] mana_detach+0x2f1/0x4e0 [mana] [ 2399.345466] ? ida_free+0x150/0x160 [ 2399.345718] ? __cond_resched+0x1a/0x50 [ 2399.345987] mana_remove+0xf4/0x1a0 [mana] [ 2399.346243] mana_gd_remove+0x25/0x80 [mana] [ 2399.346605] pci_device_remove+0x41/0xb0 [ 2399.346878] device_remove+0x46/0x70 [ 2399.347150] device_release_driver_internal+0x1e3/0x250 [ 2399.347831] ? klist_remove+0x81/0xe0 [ 2399.348377] driver_detach+0x4b/0xa0 [ 2399.348906] bus_remove_driver+0x83/0x100 [ 2399.349435] driver_unregister+0x31/0x60 [ 2399.349919] pci_unregister_driver+0x40/0x90 [ 2399.350492] mana_driver_exit+0x1c/0xb50 [mana] [ 2399.351102] __do_sys_delete_module.constprop.0+0x184/0x320 [ 2399.351664] ? __fput+0x1a9/0x2d0 [ 2399.352200] __x64_sys_delete_module+0x12/0x20 [ 2399.352760] x64_sys_call+0x1e66/0x2140 [ 2399.353316] do_syscall_64+0x79/0x150 [ 2399.353813] ? syscall_exit_to_user_mode+0x49/0x230 [ 2399.354346] ? do_syscall_64+0x85/0x150 [ 2399.354816] ? irqentry_exit+0x1d/0x30 [ 2399.355287] ? exc_page_fault+0x7f/0x160 [ 2399.355756] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 2399.356302] RIP: 0033:0x7fe728d26aeb [ 2399.356776] Code: 73 01 c3 48 8b 0d 45 33 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 15 33 0f 00 f7 d8 64 89 01 48 [ 2399.358372] RSP: 002b:00007ffff954d6f8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 [ 2399.359066] RAX: ffffffffffffffda RBX: 00005609156cc760 RCX: 00007fe728d26aeb [ 2399.359779] RDX: 000000000000000a RSI: 0000000000000800 RDI: 00005609156cc7c8 [ 2399.360535] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 2399.361261] R10: 00007fe728dbeac0 R11: 0000000000000206 R12: 00007ffff954d950 [ 2399.361952] R13: 00005609156cc2a0 R14: 00007ffff954ee5f R15: 00005609156cc760 [ 2399.362688] </TASK> Fixes: 6607c17c6c5e ("net: mana: Enable debugfs files for MANA device") Cc: stable(a)vger.kernel.org Signed-off-by: Shradha Gupta <shradhagupta(a)linux.microsoft.com> --- drivers/net/ethernet/microsoft/mana/gdma_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c index 2dc0c6ad54be..be95336ce089 100644 --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c @@ -1656,9 +1656,9 @@ static int __init mana_driver_init(void) static void __exit mana_driver_exit(void) { - debugfs_remove(mana_debugfs_root); - pci_unregister_driver(&mana_driver); + + debugfs_remove(mana_debugfs_root); } module_init(mana_driver_init); -- 2.34.1

3 months, 1 week

3
2
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+ scripts-gdb-fix-aarch64-userspace-detection-in-get_current_task.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: scripts/gdb: fix aarch64 userspace detection in get_current_task has been added to the -mm mm-hotfixes-unstable branch. Its filename is scripts-gdb-fix-aarch64-userspace-detection-in-get_current_task.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… 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: Jan Kiszka <jan.kiszka(a)siemens.com> Subject: scripts/gdb: fix aarch64 userspace detection in get_current_task Date: Fri, 10 Jan 2025 11:36:33 +0100 At least recent gdb releases (seen with 14.2) return SP_EL0 as signed long which lets the right-shift always return 0. Link: https://lkml.kernel.org/r/dcd2fabc-9131-4b48-8419-6444e2d67454@siemens.com Signed-off-by: Jan Kiszka <jan.kiszka(a)siemens.com> Cc: Barry Song <baohua(a)kernel.org> Cc: Kieran Bingham <kbingham(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- scripts/gdb/linux/cpus.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/scripts/gdb/linux/cpus.py~scripts-gdb-fix-aarch64-userspace-detection-in-get_current_task +++ a/scripts/gdb/linux/cpus.py @@ -167,7 +167,7 @@ def get_current_task(cpu): var_ptr = gdb.parse_and_eval("&pcpu_hot.current_task") return per_cpu(var_ptr, cpu).dereference() elif utils.is_target_arch("aarch64"): - current_task_addr = gdb.parse_and_eval("$SP_EL0") + current_task_addr = gdb.parse_and_eval("(unsigned long)$SP_EL0") if (current_task_addr >> 63) != 0: current_task = current_task_addr.cast(task_ptr_type) return current_task.dereference() _ Patches currently in -mm which might be from jan.kiszka(a)siemens.com are scripts-gdb-fix-aarch64-userspace-detection-in-get_current_task.patch

3 months, 1 week

1
0
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+ mm-vmscan-fix-pgdemote_-accounting-with-lru_gen_enabled.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/vmscan: fix pgdemote_* accounting with lru_gen_enabled has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmscan-fix-pgdemote_-accounting-with-lru_gen_enabled.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… 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: Li Zhijian <lizhijian(a)fujitsu.com> Subject: mm/vmscan: fix pgdemote_* accounting with lru_gen_enabled Date: Fri, 10 Jan 2025 20:21:33 +0800 Commit f77f0c751478 ("mm,memcg: provide per-cgroup counters for NUMA balancing operations") moved the accounting of PGDEMOTE_* statistics to shrink_inactive_list(). However, shrink_inactive_list() is not called when lrugen_enabled is true, leading to incorrect demotion statistics despite actual demotion events occurring. Add the PGDEMOTE_* accounting in evict_folios(), ensuring that demotion statistics are correctly updated regardless of the lru_gen_enabled state. This fix is crucial for systems that rely on accurate NUMA balancing metrics for performance tuning and resource management. Link: https://lkml.kernel.org/r/20250110122133.423481-2-lizhijian@fujitsu.com Fixes: f77f0c751478 ("mm,memcg: provide per-cgroup counters for NUMA balancing operations") Signed-off-by: Li Zhijian <lizhijian(a)fujitsu.com> Cc: Kaiyang Zhao <kaiyang2(a)cs.cmu.edu> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/vmscan.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/vmscan.c~mm-vmscan-fix-pgdemote_-accounting-with-lru_gen_enabled +++ a/mm/vmscan.c @@ -4649,6 +4649,8 @@ retry: __mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(), stat.nr_demoted); + __mod_lruvec_state(lruvec, PGDEMOTE_KSWAPD + reclaimer_offset(), + stat.nr_demoted); item = PGSTEAL_KSWAPD + reclaimer_offset(); if (!cgroup_reclaim(sc)) __count_vm_events(item, reclaimed); _ Patches currently in -mm which might be from lizhijian(a)fujitsu.com are mm-vmscan-accumulate-nr_demoted-for-accurate-demotion-statistics.patch mm-vmscan-fix-pgdemote_-accounting-with-lru_gen_enabled.patch selftests-mm-add-a-few-missing-gitignore-files.patch

3 months, 1 week

1
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+ mm-vmscan-accumulate-nr_demoted-for-accurate-demotion-statistics.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/vmscan: accumulate nr_demoted for accurate demotion statistics has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmscan-accumulate-nr_demoted-for-accurate-demotion-statistics.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… 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: Li Zhijian <lizhijian(a)fujitsu.com> Subject: mm/vmscan: accumulate nr_demoted for accurate demotion statistics Date: Fri, 10 Jan 2025 20:21:32 +0800 In shrink_folio_list(), demote_folio_list() can be called multiple times, which can lead to inaccurate demotion statistics if the number of demoted pages is not accumulated correctly. Accumulate the nr_demoted count across multiple calls to demote_folio_list(), ensuring accurate reporting of demotion statistics. Link: https://lkml.kernel.org/r/20250110122133.423481-1-lizhijian@fujitsu.com Fixes: f77f0c751478 ("mm,memcg: provide per-cgroup counters for NUMA balancing operations") Signed-off-by: Li Zhijian <lizhijian(a)fujitsu.com> Acked-by: Kaiyang Zhao <kaiyang2(a)cs.cmu.edu> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/vmscan.c~mm-vmscan-accumulate-nr_demoted-for-accurate-demotion-statistics +++ a/mm/vmscan.c @@ -1522,7 +1522,7 @@ keep: /* 'folio_list' is always empty here */ /* Migrate folios selected for demotion */ - stat->nr_demoted = demote_folio_list(&demote_folios, pgdat); + stat->nr_demoted += demote_folio_list(&demote_folios, pgdat); nr_reclaimed += stat->nr_demoted; /* Folios that could not be demoted are still in @demote_folios */ if (!list_empty(&demote_folios)) { _ Patches currently in -mm which might be from lizhijian(a)fujitsu.com are mm-vmscan-accumulate-nr_demoted-for-accurate-demotion-statistics.patch selftests-mm-add-a-few-missing-gitignore-files.patch

3 months, 1 week

1
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+ fs-proc-fix-softlockup-in-__read_vmcore-part-2.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: fs/proc: fix softlockup in __read_vmcore (part 2) has been added to the -mm mm-hotfixes-unstable branch. Its filename is fs-proc-fix-softlockup-in-__read_vmcore-part-2.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… 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: Rik van Riel <riel(a)surriel.com> Subject: fs/proc: fix softlockup in __read_vmcore (part 2) Date: Fri, 10 Jan 2025 10:28:21 -0500 Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes. In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck. The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough. Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups. Link: https://lkml.kernel.org/r/20250110102821.2a37581b@fangorn Fixes: 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") Signed-off-by: Rik van Riel <riel(a)surriel.com> Reported-by: Breno Leitao <leitao(a)debian.org> Cc: Baoquan He <bhe(a)redhat.com> Cc: Dave Young <dyoung(a)redhat.com> Cc: Vivek Goyal <vgoyal(a)redhat.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/proc/vmcore.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/proc/vmcore.c~fs-proc-fix-softlockup-in-__read_vmcore-part-2 +++ a/fs/proc/vmcore.c @@ -404,6 +404,8 @@ static ssize_t __read_vmcore(struct iov_ if (!iov_iter_count(iter)) return acc; } + + cond_resched(); } return acc; _ Patches currently in -mm which might be from riel(a)surriel.com are fs-proc-fix-softlockup-in-__read_vmcore-part-2.patch mm-remove-unnecessary-calls-to-lru_add_drain.patch

3 months, 1 week

1
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