January 2025 - Linux-stable-mirror

[PATCH v3 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 d1e263f56171..54081b1783fc 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1428,6 +1428,7 @@ 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; @@ -1470,11 +1471,26 @@ 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 @@ -1482,8 +1498,11 @@ 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); } @@ -1503,7 +1522,6 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl { struct inode *inode = folio->mapping->host; struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); - const u64 page_start = folio_pos(folio); int ret; size_t pg_offset; loff_t i_size = i_size_read(inode); @@ -1546,10 +1564,6 @@ 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(BTRFS_I(inode), folio, - page_start, PAGE_SIZE, !ret); - done: if (ret < 0) mapping_set_error(folio->mapping, ret); @@ -2329,11 +2343,8 @@ 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

5 months

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[PATCH v3 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 9725ff7f274d..d1e263f56171 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1144,12 +1144,17 @@ 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, @@ -1167,6 +1172,16 @@ 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 where our ordered extent cleanup should start. + */ + u64 last_finished_delalloc_end = page_start; u64 delalloc_start = page_start; u64 delalloc_end = page_end; u64 delalloc_to_write = 0; @@ -1235,11 +1250,19 @@ 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, @@ -1274,8 +1297,22 @@ 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; @@ -1509,13 +1546,13 @@ 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(BTRFS_I(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 8a173a24ac05..0a15473655ed 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2302,7 +2302,7 @@ 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

5 months

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[PATCH v4] arm64: mm: Populate vmemmap/linear at the page level for hotplugged sections

by Zhenhua Huang

On the arm64 platform with 4K base page config, SECTION_SIZE_BITS is set to 27, making one section 128M. The related page struct which vmemmap points to is 2M then. Commit c1cc1552616d ("arm64: MMU initialisation") optimizes the vmemmap to populate at the PMD section level which was suitable initially since hot plug granule is always one section(128M). However, commit ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") introduced a 2M(SUBSECTION_SIZE) hot plug granule, which disrupted the existing arm64 assumptions. Considering the vmemmap_free -> unmap_hotplug_pmd_range path, when pmd_sect() is true, the entire PMD section is cleared, even if there is other effective subsection. For example page_struct_map1 and page_strcut_map2 are part of a single PMD entry and they are hot-added sequentially. Then page_struct_map1 is removed, vmemmap_free() will clear the entire PMD entry freeing the struct page map for the whole section, even though page_struct_map2 is still active. Similar problem exists with linear mapping as well, for 16K base page(PMD size = 32M) or 64K base page(PMD = 512M), their block mappings exceed SUBSECTION_SIZE. Tearing down the entire PMD mapping too will leave other subsections unmapped in the linear mapping. To address the issue, we need to prevent PMD/PUD/CONT mappings for both linear and vmemmap for non-boot sections if corresponding size on the given base page exceeds 2MB(SUBSECTION_SIZE). We only permit 2MB PMD block linear mapping in 4K page size config as its PMD_SIZE matches the SUBSECTION_SIZE. Cc: stable(a)vger.kernel.org # v5.4+ Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") Signed-off-by: Zhenhua Huang <quic_zhenhuah(a)quicinc.com> --- arch/arm64/mm/mmu.c | 43 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 6 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index e2739b69e11b..5e0f514de870 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -42,9 +42,11 @@ #include <asm/pgalloc.h> #include <asm/kfence.h> -#define NO_BLOCK_MAPPINGS BIT(0) -#define NO_CONT_MAPPINGS BIT(1) -#define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */ +#define NO_PMD_BLOCK_MAPPINGS BIT(0) +#define NO_PUD_BLOCK_MAPPINGS BIT(1) /* Hotplug case: do not want block mapping for PUD */ +#define NO_BLOCK_MAPPINGS (NO_PMD_BLOCK_MAPPINGS | NO_PUD_BLOCK_MAPPINGS) +#define NO_CONT_MAPPINGS BIT(2) +#define NO_EXEC_MAPPINGS BIT(3) /* assumes FEAT_HPDS is not used */ u64 kimage_voffset __ro_after_init; EXPORT_SYMBOL(kimage_voffset); @@ -254,7 +256,7 @@ static void init_pmd(pmd_t *pmdp, unsigned long addr, unsigned long end, /* try section mapping first */ if (((addr | next | phys) & ~PMD_MASK) == 0 && - (flags & NO_BLOCK_MAPPINGS) == 0) { + (flags & NO_PMD_BLOCK_MAPPINGS) == 0) { pmd_set_huge(pmdp, phys, prot); /* @@ -356,10 +358,11 @@ static void alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end, /* * For 4K granule only, attempt to put down a 1GB block + * Hotplug case: do not attempt 1GB block */ if (pud_sect_supported() && ((addr | next | phys) & ~PUD_MASK) == 0 && - (flags & NO_BLOCK_MAPPINGS) == 0) { + (flags & NO_PUD_BLOCK_MAPPINGS) == 0) { pud_set_huge(pudp, phys, prot); /* @@ -1175,9 +1178,21 @@ int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node, int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, struct vmem_altmap *altmap) { + unsigned long start_pfn; + struct mem_section *ms; + WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); - if (!IS_ENABLED(CONFIG_ARM64_4K_PAGES)) + start_pfn = page_to_pfn((struct page *)start); + ms = __pfn_to_section(start_pfn); + + /* + * Hotplugged section does not support hugepages as + * PMD_SIZE (hence PUD_SIZE) section mapping covers + * struct page range that exceeds a SUBSECTION_SIZE + * i.e 2MB - for all available base page sizes. + */ + if (!IS_ENABLED(CONFIG_ARM64_4K_PAGES) || !early_section(ms)) return vmemmap_populate_basepages(start, end, node, altmap); else return vmemmap_populate_hugepages(start, end, node, altmap); @@ -1339,9 +1354,25 @@ int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { int ret, flags = NO_EXEC_MAPPINGS; + unsigned long start_pfn = page_to_pfn((struct page *)start); + struct mem_section *ms = __pfn_to_section(start_pfn); VM_BUG_ON(!mhp_range_allowed(start, size, true)); + /* should not be invoked by early section */ + WARN_ON(early_section(ms)); + + /* + * 4K base page's PMD_SIZE matches SUBSECTION_SIZE i.e 2MB. Hence + * PMD section mapping can be allowed, but only for 4K base pages. + * Where as PMD_SIZE (hence PUD_SIZE) for other page sizes exceed + * SUBSECTION_SIZE. + */ + if (IS_ENABLED(CONFIG_ARM64_4K_PAGES)) + flags |= NO_PUD_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; + else + flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; + if (can_set_direct_map()) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; -- 2.25.1

5 months

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[PATCH v2] usb: dwc3-am62: Fix an OF node leak in phy_syscon_pll_refclk()

by Joe Hattori

phy_syscon_pll_refclk() leaks an OF node obtained by of_parse_phandle_with_fixed_args(), thus add an of_node_put() call. Cc: stable(a)vger.kernel.org Fixes: e8784c0aec03 ("drivers: usb: dwc3: Add AM62 USB wrapper driver") Signed-off-by: Joe Hattori <joe(a)pf.is.s.u-tokyo.ac.jp> --- Changes in v2: - Add the stable tag. --- drivers/usb/dwc3/dwc3-am62.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c index 5e3d1741701f..0a33ed958ebb 100644 --- a/drivers/usb/dwc3/dwc3-am62.c +++ b/drivers/usb/dwc3/dwc3-am62.c @@ -166,6 +166,7 @@ static int phy_syscon_pll_refclk(struct dwc3_am62 *am62) if (ret) return ret; + of_node_put(args.np); am62->offset = args.args[0]; /* Core voltage. PHY_CORE_VOLTAGE bit Recommended to be 0 always */ -- 2.34.1

5 months

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[PATCH v2] phy: Fix error handling in tegra_xusb_port_init

by Ma Ke

If device_add() fails, do not use device_unregister() for error handling. device_unregister() consists two functions: device_del() and put_device(). device_unregister() should only be called after device_add() succeeded because device_del() undoes what device_add() does if successful. Change device_unregister() to put_device() call before returning from the function. As comment of device_add() says, 'if device_add() succeeds, you should call device_del() when you want to get rid of it. If device_add() has not succeeded, use only put_device() to drop the reference count'. Found by code review. Cc: stable(a)vger.kernel.org Fixes: 53d2a715c240 ("phy: Add Tegra XUSB pad controller support") Signed-off-by: Ma Ke <make24(a)iscas.ac.cn> --- Changes in v2: - modified the bug description as suggestions. --- drivers/phy/tegra/xusb.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c index 79d4814d758d..c89df95aa6ca 100644 --- a/drivers/phy/tegra/xusb.c +++ b/drivers/phy/tegra/xusb.c @@ -548,16 +548,16 @@ static int tegra_xusb_port_init(struct tegra_xusb_port *port, err = dev_set_name(&port->dev, "%s-%u", name, index); if (err < 0) - goto unregister; + goto put_device; err = device_add(&port->dev); if (err < 0) - goto unregister; + goto put_device; return 0; -unregister: - device_unregister(&port->dev); +put_device: + put_device(&port->dev); return err; } -- 2.25.1

5 months

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+ mm-vmscan-pgdemote-vmstat-is-not-getting-updated-when-mglru-is-enabled.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: vmscan : pgdemote vmstat is not getting updated when MGLRU is enabled. has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmscan-pgdemote-vmstat-is-not-getting-updated-when-mglru-is-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: Donet Tom <donettom(a)linux.ibm.com> Subject: mm: vmscan : pgdemote vmstat is not getting updated when MGLRU is enabled. Date: Thu, 9 Jan 2025 00:05:39 -0600 When MGLRU is enabled, the pgdemote_kswapd, pgdemote_direct, and pgdemote_khugepaged stats in vmstat are not being updated. Commit f77f0c751478 ("mm,memcg: provide per-cgroup counters for NUMA balancing operations") moved the pgdemote vmstat update from demote_folio_list() to shrink_inactive_list(), which is in the normal LRU path. As a result, the pgdemote stats are updated correctly for the normal LRU but not for MGLRU. To address this, we have added the pgdemote stat update in the evict_folios() function, which is in the MGLRU path. With this patch, the pgdemote stats will now be updated correctly when MGLRU is enabled. Without this patch vmstat output when MGLRU is enabled ====================================================== pgdemote_kswapd 0 pgdemote_direct 0 pgdemote_khugepaged 0 With this patch vmstat output when MGLRU is enabled =================================================== pgdemote_kswapd 43234 pgdemote_direct 4691 pgdemote_khugepaged 0 Link: https://lkml.kernel.org/r/20250109060540.451261-1-donettom@linux.ibm.com Fixes: f77f0c751478 ("mm,memcg: provide per-cgroup counters for NUMA balancing operations") Signed-off-by: Donet Tom <donettom(a)linux.ibm.com> Acked-by: Yu Zhao <yuzhao(a)google.com> Cc: Aneesh Kumar K.V (Arm) <aneesh.kumar(a)kernel.org> Cc: David Rientjes <rientjes(a)google.com> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: Kaiyang Zhao <kaiyang2(a)cs.cmu.edu> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Muchun Song <muchun.song(a)linux.dev> Cc: Ritesh Harjani (IBM) <ritesh.list(a)gmail.com> Cc: Roman Gushchin <roman.gushchin(a)linux.dev> Cc: Shakeel Butt <shakeel.butt(a)linux.dev> Cc: Wei Xu <weixugc(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/vmscan.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/vmscan.c~mm-vmscan-pgdemote-vmstat-is-not-getting-updated-when-mglru-is-enabled +++ a/mm/vmscan.c @@ -4646,6 +4646,9 @@ retry: reset_batch_size(walk); } + __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 donettom(a)linux.ibm.com are mm-vmscan-pgdemote-vmstat-is-not-getting-updated-when-mglru-is-enabled.patch mm-migrate-removed-unused-argument-vma-from-migrate_misplaced_folio.patch selftests-mm-added-new-test-cases-to-the-migration-test.patch

5 months

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[PATCH v2 5/9] btrfs: do proper folio cleanup when run_delalloc_nocow() failed

by Qu Wenruo

[BUG] With CONFIG_DEBUG_VM set, test case generic/476 has some chance to crash with the following VM_BUG_ON_FOLIO(): BTRFS error (device dm-3): cow_file_range failed, start 1146880 end 1253375 len 106496 ret -28 BTRFS error (device dm-3): run_delalloc_nocow failed, start 1146880 end 1253375 len 106496 ret -28 page: refcount:4 mapcount:0 mapping:00000000592787cc index:0x12 pfn:0x10664 aops:btrfs_aops [btrfs] ino:101 dentry name(?):"f1774" flags: 0x2fffff80004028(uptodate|lru|private|node=0|zone=2|lastcpupid=0xfffff) page dumped because: VM_BUG_ON_FOLIO(!folio_test_locked(folio)) ------------[ cut here ]------------ kernel BUG at mm/page-writeback.c:2992! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP CPU: 2 UID: 0 PID: 3943513 Comm: kworker/u24:15 Tainted: G OE 6.12.0-rc7-custom+ #87 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 : folio_clear_dirty_for_io+0x128/0x258 lr : folio_clear_dirty_for_io+0x128/0x258 Call trace: folio_clear_dirty_for_io+0x128/0x258 btrfs_folio_clamp_clear_dirty+0x80/0xd0 [btrfs] __process_folios_contig+0x154/0x268 [btrfs] extent_clear_unlock_delalloc+0x5c/0x80 [btrfs] run_delalloc_nocow+0x5f8/0x760 [btrfs] btrfs_run_delalloc_range+0xa8/0x220 [btrfs] writepage_delalloc+0x230/0x4c8 [btrfs] extent_writepage+0xb8/0x358 [btrfs] extent_write_cache_pages+0x21c/0x4e8 [btrfs] btrfs_writepages+0x94/0x150 [btrfs] do_writepages+0x74/0x190 filemap_fdatawrite_wbc+0x88/0xc8 start_delalloc_inodes+0x178/0x3a8 [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: 910a8021 a90363f7 a9046bf9 94012379 (d4210000) ---[ end trace 0000000000000000 ]--- [CAUSE] The first two lines of extra debug messages show the problem is caused by the error handling of run_delalloc_nocow(). E.g. we have the following dirtied range (4K blocksize 4K page size): 0 16K 32K |//////////////////////////////////////| | Pre-allocated | And the range [0, 16K) has a preallocated extent. - Enter run_delalloc_nocow() for range [0, 16K) Which found range [0, 16K) is preallocated, can do the proper NOCOW write. - Enter fallback_to_fow() for range [16K, 32K) Since the range [16K, 32K) is not backed by preallocated extent, we have to go COW. - cow_file_range() failed for range [16K, 32K) So cow_file_range() will do the clean up by clearing folio dirty, unlock the folios. Now the folios in range [16K, 32K) is unlocked. - Enter extent_clear_unlock_delalloc() from run_delalloc_nocow() Which is called with PAGE_START_WRITEBACK to start page writeback. But folios can only be marked writeback when it's properly locked, thus this triggered the VM_BUG_ON_FOLIO(). Furthermore there is another hidden but common bug that run_delalloc_nocow() is not clearing the folio dirty flags in its error handling path. This is the common bug shared between run_delalloc_nocow() and cow_file_range(). [FIX] - Clear folio dirty for range [@start, @cur_offset) Introduce a helper, cleanup_dirty_folios(), which will find and lock the folio in the range, clear the dirty flag and start/end the writeback, with the extra handling for the @locked_folio. - Introduce a helper to record the last failed COW range end This is to trace which range we should skip, to avoid double unlocking. - Skip the failed COW range for the error handling Cc: stable(a)vger.kernel.org Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/inode.c | 93 ++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 86 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 19c88b7d0363..bae8aceb3eae 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1961,6 +1961,48 @@ static int can_nocow_file_extent(struct btrfs_path *path, return ret < 0 ? ret : can_nocow; } +static void cleanup_dirty_folios(struct btrfs_inode *inode, + struct folio *locked_folio, + u64 start, u64 end, int error) +{ + struct btrfs_fs_info *fs_info = inode->root->fs_info; + struct address_space *mapping = inode->vfs_inode.i_mapping; + pgoff_t start_index = start >> PAGE_SHIFT; + pgoff_t end_index = end >> PAGE_SHIFT; + u32 len; + + ASSERT(end + 1 - start < U32_MAX); + ASSERT(IS_ALIGNED(start, fs_info->sectorsize) && + IS_ALIGNED(end + 1, fs_info->sectorsize)); + len = end + 1 - start; + + /* + * Handle the locked folio first. + * btrfs_folio_clamp_*() helpers can handle range out of the folio case. + */ + btrfs_folio_clamp_clear_dirty(fs_info, locked_folio, start, len); + btrfs_folio_clamp_set_writeback(fs_info, locked_folio, start, len); + btrfs_folio_clamp_clear_writeback(fs_info, locked_folio, start, len); + + for (pgoff_t index = start_index; index <= end_index; index++) { + struct folio *folio; + + /* Already handled at the beginning. */ + if (index == locked_folio->index) + continue; + folio = __filemap_get_folio(mapping, index, FGP_LOCK, GFP_NOFS); + /* Cache already dropped, no need to do any cleanup. */ + if (IS_ERR(folio)) + continue; + btrfs_folio_clamp_clear_dirty(fs_info, folio, start, len); + btrfs_folio_clamp_set_writeback(fs_info, folio, start, len); + btrfs_folio_clamp_clear_writeback(fs_info, folio, start, len); + folio_unlock(folio); + folio_put(folio); + } + mapping_set_error(mapping, error); +} + /* * when nowcow writeback call back. This checks for snapshots or COW copies * of the extents that exist in the file, and COWs the file as required. @@ -1976,6 +2018,11 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, struct btrfs_root *root = inode->root; struct btrfs_path *path; u64 cow_start = (u64)-1; + /* + * If not 0, represents the inclusive end of the last fallback_to_cow() + * range. Only for error handling. + */ + u64 cow_end = 0; u64 cur_offset = start; int ret; bool check_prev = true; @@ -2136,6 +2183,7 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, found_key.offset - 1); cow_start = (u64)-1; if (ret) { + cow_end = found_key.offset - 1; btrfs_dec_nocow_writers(nocow_bg); goto error; } @@ -2209,11 +2257,12 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, cow_start = cur_offset; if (cow_start != (u64)-1) { - cur_offset = end; ret = fallback_to_cow(inode, locked_folio, cow_start, end); cow_start = (u64)-1; - if (ret) + if (ret) { + cow_end = end; goto error; + } } btrfs_free_path(path); @@ -2221,12 +2270,42 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode, error: /* - * If an error happened while a COW region is outstanding, cur_offset - * needs to be reset to cow_start to ensure the COW region is unlocked - * as well. + * There are several error cases: + * + * 1) Failed without falling back to COW + * start cur_start end + * |/////////////| | + * + * For range [start, cur_start) the folios are already unlocked (except + * @locked_folio), EXTENT_DELALLOC already removed. + * Only need to clear the dirty flag as they will never be submitted. + * Ordered extent and extent maps are handled by + * btrfs_mark_ordered_io_finished() inside run_delalloc_range(). + * + * 2) Failed with error from fallback_to_cow() + * start cur_start cow_end end + * |/////////////|-----------| | + * + * For range [start, cur_start) it's the same as case 1). + * But for range [cur_start, cow_end), the folios have dirty flag + * cleared and unlocked, EXTENT_DEALLLOC cleared. + * There may or may not be any ordered extents/extent maps allocated. + * + * We should not call extent_clear_unlock_delalloc() on range [cur_start, + * cow_end), as the folios are already unlocked. + * + * So clear the folio dirty flags for [start, cur_offset) first. */ - if (cow_start != (u64)-1) - cur_offset = cow_start; + if (cur_offset > start) + cleanup_dirty_folios(inode, locked_folio, start, cur_offset - 1, ret); + + /* + * If an error happened while a COW region is outstanding, cur_offset + * needs to be reset to @cow_end + 1 to skip the COW range, as + * cow_file_range() will do the proper cleanup at error. + */ + if (cow_end) + cur_offset = cow_end + 1; /* * We need to lock the extent here because we're clearing DELALLOC and -- 2.47.1

5 months

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[PATCH v2 4/9] 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 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 5ba8d044757b..19c88b7d0363 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1364,6 +1364,17 @@ 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 @@ -1423,6 +1434,10 @@ 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); @@ -1468,21 +1483,6 @@ 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 @@ -1499,6 +1499,9 @@ 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; @@ -1519,35 +1522,31 @@ 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

5 months

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[PATCH v2 2/9] 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 | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 417c710c55ca..b6a4f1765b4c 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1418,6 +1418,7 @@ 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; @@ -1460,11 +1461,21 @@ 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)) { + 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 @@ -1472,8 +1483,11 @@ 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); } @@ -1493,7 +1507,6 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl { struct inode *inode = folio->mapping->host; struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); - const u64 page_start = folio_pos(folio); int ret; size_t pg_offset; loff_t i_size = i_size_read(inode); @@ -1536,10 +1549,6 @@ 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(BTRFS_I(inode), folio, - page_start, PAGE_SIZE, !ret); - done: if (ret < 0) mapping_set_error(folio->mapping, ret); @@ -2319,11 +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

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[PATCH] drm/xe/client: Better correlate exec_queue and GT timestamps

by Lucas De Marchi

This partially reverts commit fe4f5d4b6616 ("drm/xe: Clean up VM / exec queue file lock usage."). While it's desired to have the mutex to protect only the reference to the exec queue, getting and dropping each mutex and then later getting the GPU timestamp, doesn't produce a correct result: it introduces multiple opportunities for the task to be scheduled out and thus wrecking havoc the deltas reported to userspace. Also, to better correlate the timestamp from the exec queues with the GPU, disable preemption so they can be updated without allowing the task to be scheduled out. We leave interrupts enabled as that shouldn't be enough disturbance for the deltas to matter to userspace. Test scenario: * IGT'S `xe_drm_fdinfo --r --r utilization-single-full-load` * Platform: LNL, where CI occasionally reports failures * `stress -c $(nproc)` running in parallel to disturb the system This brings a first failure from "after ~150 executions" to "never occurs after 1000 attempts". Cc: stable(a)vger.kernel.org # v6.11+ Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3512 Signed-off-by: Lucas De Marchi <lucas.demarchi(a)intel.com> --- drivers/gpu/drm/xe/xe_drm_client.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_drm_client.c b/drivers/gpu/drm/xe/xe_drm_client.c index 298a587da7f17..e307b4d6bab5a 100644 --- a/drivers/gpu/drm/xe/xe_drm_client.c +++ b/drivers/gpu/drm/xe/xe_drm_client.c @@ -338,15 +338,12 @@ static void show_run_ticks(struct drm_printer *p, struct drm_file *file) /* Accumulate all the exec queues from this client */ mutex_lock(&xef->exec_queue.lock); - xa_for_each(&xef->exec_queue.xa, i, q) { - xe_exec_queue_get(q); - mutex_unlock(&xef->exec_queue.lock); + preempt_disable(); + xa_for_each(&xef->exec_queue.xa, i, q) xe_exec_queue_update_run_ticks(q); - mutex_lock(&xef->exec_queue.lock); - xe_exec_queue_put(q); - } + preempt_enable(); mutex_unlock(&xef->exec_queue.lock); gpu_timestamp = xe_hw_engine_read_timestamp(hwe); -- 2.47.0

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